I don't know if you ever see the ifixit tear downs, there is no new tricks. The battery is still replaceable, it's just that the manufacturing process adds more stuff to "anti-tempering". Let me list a few:

• special kind of screw, some screw can't be unscrewed without special screw driver
• we all know about glue battery so they are fixed in place AND harder to remove safely.
• they add more of those tiny ribbon around so if you don't know the internal layout there is a chance you break the ribbon.
• plastic wedge that might be broken when you try to pry it open(so when you put the cover back it's a bit loose, and lose water resist), even with proper tool. They designed it so it was not suppose to open again. ( I have a old casio slim camera that can still be water resistant with removable battery, there is no reason why a phone can't do the same with modern materials. )