No its happened.
Microsoft are not going to spend $7 billion and destroy it. Today's Microsoft isn't the Microsoft of the 80s / 90s: they are embracing Open Source, contributing, and supporting non-microsoft operating systems, notable, Linux. There's a lot worse companies that could have bought GitHub instead, i.e., Oracle.
I'd rather Microsoft have bought it, than say Apple, would would close it down instantly and make it an Apple only service, leaving GitHub shadow of its former self. Not that Apple would ever buy GitHub, because they are primarily a consumer facing company these days.
Microsoft have purchased Skype, LinkedIn, and they aren't worse off than they were beforehand.
People seriously need to live in the 2018s, instead of remembering the Microsoft of old, under Gates and Balmer.