It's official: Smartphones will need to have replaceable batteries by 2027
(www.androidauthority.com)
I had a Galaxy S5 which I think was IP67 (someone fact check me on that), and a removable battery. It definitely didn't have a premium feel, and it got eviscerated in reviews for that. That didn't bother me though. Though, the backing cracked and the little plastic clips broke off rather quickly. I think if they had a metal backing that was held on by a regular (albeit tiny) Philips head screw(s), they could have a user replaceable battery on a premium phone with IP68 no problem.