Also, it will make economic sense for phone manufacturers to have as few battery models as possible. So, it’s possible that there are some pretty standard batteries. It’s also the case that batteries that sit in a warehouse for years are still better than batteries that have been discharged and recharged repeatedly.

I’ve paid a technician to replace the non-replaceable battery in one iPhone and in one iPad. Even though Apple doesn’t officially make batteries replaceable, if you are willing to pay for it, you can get a new battery and extend the life of your device by a couple of years. I imagine that will only get easier once the batteries are actually user replaceable.