Is just making GitHub better worth $7.5 billion dollars for Microsoft? It will stay independent for this pile of cash? Why they bought it? For prestige?
For me the answer is that it can't be independent for long as it was (with VCs on its back was it ever?). It will gain Live login, maybe they will integrate it so you could login with your GitHub credentials to your computer if you so desire. But that's hardly worth billions.
Maybe the better thing would be what others suggested - setup a non-profit that would run GitHub and all those big companies could put something in the jar. Certainly less than what was paid. But I know it can't work, VCs want their exit.
For me it's a same game for GitLab. Current situation probably will accelerate GitLab's burn rate so prepare for the next acquisition.