EU: Smartphones Must Have User-Replaceable Batteries by 2027:
https://www.pcmag.com/news/eu-smartphones-must-have-user-replaceable-batteries-by-2027
I loved having a replaceable battery on my Samsung S3. Phones won’t be completely waterproof, but I would rather be able to replace the battery. It will be interesting to see what Apple does as I don’t believe they have ever used user-replaceable batteries.
There are some users (raises hand) for whom any battery that is not rigged to self-destruct if accessed is replaceable. I replaced the battery in my Nexus 6P twice before it failed due what turned out to be a known manufacturing defect. I am a bit of an outlier in that sense. 
The Samsung Galaxy xcover6 pro has an easy to remove battery and an IP68 rating. Phone designs will need to be a bit different but it can be done. I’ve changed a few iphone and Android batteries so I don’t mind taking a phone apart myself but that definitely is not for everyone.