[s0rce]

While having it externally accessible for trivial swapping is nice, the obvious downside is that it can come out inadvertently. A compromise where it is behind a screwed down panel and held in place with a connect (not soldered). This would mean easy replacement either by either by the end user, an authorized repair shop or apple. I don't really see this as any different than routine maintenance and replacement of car parts. If Apple charged 5x battery replacement costs compared to other phone vendors then this might cost them marketshare, however, people still buy fancy cars where parts are much more expensive.

[mikeash]

This is what Apple does. They'll replace your battery for $79. Third parties will do it for a bit less. Doing it yourself requires a weird screwdriver and some other tools, but isn't terribly hard, and you can get a kit with a new battery and all the required tools for $25.