For all the complaints about Microsoft, I've yet to hear what they could do that would be so bad? Change the homepage to actually be useful? Improve the search? Give away free private repos?
But even so: I agree the fear that the product will be worse in a few feels completely irrational.
What I can agree with is that it’s unfortunate that it’s no longer seen as a neutral ground for development. It felt almost like a standard or like a piece of infrastructure, rather than a for-profit. But that was of course never the case. But now it becomes obvious, which might fracture the community (it was very nice to have everything in one place - e.g package managers literally started drawing stuff from github links). The appearance of neutrality and trust was the #1 feature of GitHub. Everything else is polish. Microsoft will have to work hard to keep the #1 feature working.
That's very different from killing it, but it could make developing or supporting Electron apps more difficult - plus the fear that it could then start sliding down the slope of the Windows version getting more investment, eventually leading to the classic "it's best on Windows" embrace/extend platform lockin. I'm not betting on that being their play, but I could see how people would worry...
Github is very little about git and mostly about the hub. The inertia is in the issue tracker, forks/stars/...
From this point of view, speculation about what Microsoft could do is redundant; whatever they do, including nothing at all, will be considered suspect unless obviously harmful.
- Worsen the usability of the site, introduce dark patterns
- Steal users' code (it has been rumored to happen before)
- Introduce mandatory usage of Microsoft accounts
- Gain a competitive advantage by spying on competitors' private repos
- Sell information about the users to the highest bidder