With the changes being made, I wouldn't be surprised if a Linux phone has a real chance.

I assume it will still be possible to enable the APIs with adb.

So this will mostly affect users in that in-between skill level where they know how to use a third-party app store (or how to download and install apps from a file browser) but don't know how to use adb. I'm not so sure how big that segment is. Probably pretty small.

For the group of users who are tech-illiterate (the common case), this is actually a very welcome change for malware prevention.