> Will probably cost a lot to redesign everything

I wouldn't think too much cost, since targeting 2027 means it should only affect phones that aren't even designed yet? (At least, I don't think anyone is taking 3-4 years to get a phone to market)

I'm thinking of all the things that are reused between product generations, from form factors to manufacturing processes.

I don't know about Apple, but Samsung seems to have figured that going the other way, from replaceable battery to non-replaceable, made sense. I doubt it would cost them that much in engineering to go back to that.