Ultimately Linux audio is in a very difficult situation with no easy and cheap solution. The best solution I can think of going forward would be to strip down and fork ALSA into a new branch- that way you could fix alot of the architectural problems while retaining alot of the nicer features, keeping users happy because they can fall back on legacy ALSA if they need the features not yet implemented in the newer versions.
Pushing OSSv4 into the main distributions would do nothing but cause problems, since you'll have two APIs fighting for the same hardware, or you will end up using an emulation layer which potentially creates all of the problems outlined in this thread anyway.
OSS is considered deprecated by many and there is alot of resistance to it showing up in newer distros for a good reason- it would be backtracking to a less functional state with no immediate or long term advantages. This is not even getting into the politics and (lack of) trust the Open Source community has for the architecture and its developers.