Re: Alternate operating systems
If they get rid of the compatibility tests, it will also make it fun to try and find apps that work as expected with your phone. Back to the good old days of early Android. Those apps with embedded maps? They won't work on phones without the maps APIs. You want to monetise? You'll need to implement a load of different payment APIs for all the stores.
A lot of the APIs were moved in to other services from core Android, so that they could be updated without a full firmware update. That's pretty important as a lot of carriers and manufacturers rarely provide firmware updates.
Ideally (from my point of view) they'd move even more of them out so that even more security and other bug fixes could be easily fixed. For example, the stagefright bugs weren't able to be fixed without a firmware update, as they were in the core OS.