Android

A fucking headphone jack

Apparently most of my requirements/desires fit this. I require an unlocked bootloader, because I need root to not throw my phone through a window. An amazing camera would be needed as well.

I REALLY, REALLY would like a removable battery, IR blaster, small form function, a headphone jack, and a rear fingerprint reader.

HEADPHONE JACK.

GIVE ME THE GOD DAMN HEADPHONE JACK BACK

I miss having a notification LED. It used to be super common to have a "breathing" effect with a given color when an app had sent a notification.

So a Snapchat for example would show the breathing as yellow, etc. Super convenient to check for messages without going and grabbing the phone.

Headset jack and let me replace my damn battery. Also default option to uninstall non-OEM apps

sideloading is a requirement for me and unlockable bootloader, otherwise, some things like an IR blaster, headphone jack, removable battery (thx EU), RGB notification LED, front facing speakers would make a "good" phone become "great"

I'd like a phone with no camera facing me, and physical hardware switches to completely disable the mic, camera, battery, and entire modem. Not some software interrupt and lock. I mean, the switch is circuit ground for these circuit blocks. When I select OFF, it means real world "this thing does not exist any more ever" until I turn it back on.

It would be interesting to have a modular rear camera with a removable lens, removable IR filter, along with public documentation and the full API for the sensor. This would open up an enormous range of applications. I would mostly mess with astrophotography more.

I know some phones had already did this, but I always liked the idea of support for using your phone as a TV remote. The phone has replaced so many pieces of hardware that it feels silly that TV remotes haven't been replaced yet.

I also specifically wish Chrome supported extensions on mobile. Firefox does it. Why can't the biggest browser do it?

An open bootloader and a removable battery.

There are some niche phones with a thermal camera, would love to see more of that. Thermal modules are getting smaller, cheaper and better all the time and the main producers like infiray or guide are offering modules that seem to be clearly targeted at the smartphone market.

I'm still discovering new uses for my thermal camera and I wish I could have it in my pocket all the time. The obvious uses are finding gaps in your house's thermal insulation or finding devices that draw a lot of standby energy. But you can also use it to find studs in your walls, find things that have recently been used, like cars in a parking lot or chairs in an office.

Headphone socket. They are taking away what was a universal feature and replacing it with inconvenient crap.

I want a Galaxy Fold style phone, but the external screen is eInk. Have it set to always show the book I am reading. This will let me read in bite sized pieces.

E-Ink would be nice, whether integrated as part of an OLED/LCD screen, or a separate module that goes over the top.

Most of the things that I use my phone for don't generally need the full colour display (text isn't that expensive to display), and I wouldn't mind trading that for vastly better battery life that you can get from e-ink, but having the option to use both is probably the best way to go.

An IR transceiver wouldn't go poorly either. It's not something I use much, but it was handy to have when I did, whether to send things around, or to just use my phone as a remote for televisions and things.

Modular everything. I really wanted Project Ara to come to market.

OMG great question! I want:

• Laser range finder/"tape" measure
• Thermal camera
• Air quality sensor
• Radiation detector/Geiger counter
• Multimeter capabilities
• IR LED (so I can use it as a remote)
• Ultrasound capabilities
• Peltier so I can put a drink on my phone to chill it down 👍

Slide out physical keyboard, notification LEDs or some form of cool lights, a dedicated camera shutter button, and a scroll wheel / touch pad like what used to be on the blackberry or like the LG KE970 I really liked that.

I really miss notification LED's though, always on display is good, but a little light is going to use far less battery and be immediately apparent from across the room by the colour what app the notification came from is.

edit : formatting

Late to the thread but here's my thoughts:

Hardware:

1. Standard features like a 3.5mm jack and MicroSD slot.
2. Multiple USB ports (especially on tablets)
3. Thunderbolt port
4. Here's a simple idea: Instead of making a thin phone with a massive camera bump, you make a thick phone with the camera flush with the back, and use the extra space for a bigger battery?
5. User-replacable battery
6. Modules like the modo mods
7. Battery passthrough when charging
8. Upgradable RAM, internal storage???

Software (here lies my hopes and dreams that will never be manifested):

1. Starting off simple, a feature that lets you manually limit how much you charge your battery.
2. Manual over/underclocking controls for the CPU
3. Separate WiFi/data toggles
4. More control over how big or small icons and text is
5. Easy root access with app makers not getting all "you sus" over the fact that your device is rooted
6. No data harvesting (duh)
7. Better file management (and removing scoped storage)
8. Multiple logins to a phone (like what you can do with a desktop)
9. One app, multiple accounts
10. Just having the software take less system resources.
11. Open sourcing hardware drivers
12. Multiple floating windows like with a desktop OS
13. More than 3 split screen options
14. I'm sure there's a lot more I can't think of now

A phone built somewhat like a desktop PC. All parts replaceable or even upgradable. Choose the components for your needs and budget, or buy a pre-built.
But let's get to more standard smartphone concept.
On software side, no bootloader locks, or easily unlockable bootloader (not requiring internet) and root access that could be enabled in developer settings.

On hardware side:
IR blaster - Control your AC, TV, etc.
Front-facing stereo speakers - could give a better stereo sound. And bezels aren't a big problem. Actually they can be positive as you can hold your phone better with them.
Headphone jack - Obvious. Would be cool if it had mode for composite output, but that's quite extra.
Dedicated fingerprint scanner on front - I had this on Moto G5s Plus. It allowed awesome gesture navigation, much better than using whatever on-screen.
Trackpoint - Early Androids used to have that. Would definitely be useful with large screens.
FM, HD Radio, DAB, DAB+, DVB-T2 Lite receiver - Radio is pretty useful. AM would also be nice, though you would need external antenna better than cable from earphones. I think FM radio is the minimum here.
TV Receiver - Just like with radio, except now you're saving much more on mobile data.
Camera with optical zoom - We've been there with Samsung in the past. But I understand it makes things too large and heavy.
Projector - We've been there with Samsung in the past, again. I think it was done pretty nicely on the projector part with Beam 2. It didn't even add much thickness. Just the rest of the phone was meh.

IR emitter . Super handy wen you use old stuf like me like VHS dvd combo crt ect .

I was looking into smaller form factor phones awhile back, and an interesting feature I noticed some of them had was a programmable button.

I don't know that programmable buttons on phones are that niche, but it's certainly not common either so far as I'm aware, so this super simple feature would be wicked imo. I'd also really like if more phones just stole Motorola's gesture interactions (e.g. quick twist for camera, firm double-shake for flashlight, etc.).

Also, uh...Speaking of small form factor phones, I don't know if that counts as a feature, but it's one detail I'd like to see come back, or flip phones with separate screens (clunky, sure, but better than the screen eventually creasing imo).

I miss my keyboards

Whenever I buy a phone there's two function I look for that is getting phased out: LED indicator and a 3.5mm audio jack. It's why I have a Sony Xperia. The thing is there's no user configuration for the LED indicator. You either need to pay for a third party app or unlock the bootloader and install a custom firmware. I would love if a flagship phone had an LED Indicstor that was customizable. i.e. Blue for a text, Red for an email, Green for battery at 80%+, etc.

Oh I forgot, a clamshell folding phone but with only one screen and the other side is a physical keyboard, like a mini-laptop.

Nobody seems really know how to do a folding screen well, so why have the screen fold at all?

An ir blaster, great as a universal remote

Larger, swappable battery. Squeeze for assistant

More phones like the Fairphone/Framework Laptop. Easy to repair and upgrade in a modular manner, as well as install what ever OS I choose.

I want a phone small enough to fit in my pocket with the pocket flap buttoned shut

Something interesting. Like 2 USB-C ports, also a nice hard plastic back, since they are so hard to find now.

A phone without the actual phone part. Just SMS/MMS. Maybe a notification that someone tried to call

I miss the IR blaster. Being able to control my TV and other set-top boxes was amazing. Now that functionality has been replaced by each manufacturer having their own control app that needs an internet connection and all your information. Bring back the IR blaster!

Niche or not, I want an SD card slot that actually fucking works. Like, yes, I can move files to it, but I can't actually install apps to it. There's the "move to SD, but that doesn't matter when the app files are still stored on the internal storage.

Honestly, headphone jacks are number 1.

Then also, FM radios. Most Android phones had them up until a few years ago, when Apple stopped shipping iphones with the feature, to push more people onto iTunes. I'm not a huge radio listener. But having the functionality during an emergency is invaluable. There was a really bad storm in my country a few years ago. Me and my family had no power and no internet for nearly a week. I would listen to my battery powered radio to get weather updates and to find out what the situation was like elsewhere. I don't understand why that same functionality can't be implemented in phones.

Besides that, removable batteries, sim card and SD card slots.

An OEM FM/AM transmitter. I would love to be able to playback music directly to any old ass car. Or even use it as a very short range walkie talkie with the right program.

I miss my IR blaster.

I'm on a Fold 4 now and I do love the novelty/oddity aspect of having a folding tablet.

But I would love to see the return of IR blasters on most phones and sliding phones for physical keyboards.

Slide out controller, like the Xperia Play. I've gotten super into (at least the idea of) SBC handheld gaming, and there's just nothing quite like the Xperia Play now. Sure, there's bluetooth controllers, but I'm not a big fan of bluetooth, and the majority of the bluetooth controllers make portability a pain rather than it being a sleek package.

Phone upgrades.
Battery.. Non lithuim. Flexible and new. []
Flexible screen. Wrist strap or just flexible. []
Fitness/health capabilities. []
Usb 3.1 reversible.. Proper specs [x]
Wireless charging. Using new WiFi microwave to charge phone without mat. Wattup []
Better nfc/Google pay [x]
Smaller screen oled,s than 5.5 []
Better speakers none conduction or ceramic
Encryption []
Bezelless. Screen to screen hole cut out. 2018 []
Solar panel in screen. Sapphire glass. Smudge and germ

This list was created a few years ago.

Some things have been implemented but not all.

Really would love a dedicated camera button that acts as a soft shutter release. Or a button in that position that's programmable.