Here's the official GitHub Statement and a blog post from Nadella.
I wouldn't make this so much about feelings. Let's face it: Microsoft is not evil. But Microsoft isn't necessarily good, either. Microsoft is just a very big company doing what they think is best for their business, and that doesn't always mean it's what's best for everyone else. And yes, they're dabbling with some open-source stuff, but only where it's required or at least very difficult to justify not to have it open. Microsoft wants to stay in control. They already lost the windows-server market to the "foss revolution", so they understood that they have to join the winning team if they want to stay on top. That alone doesn't make them evil. In fact, most companies work that way (even GitHub always has, that's why the GitHub server is proprietary), but they could still change. So let's give them credit for embracing foss where they are and encourage them to abandon their proprietary projects and selfish business techniques. They're saying they aren't the enemy, let's believe them that. But that doesn't automatically make them our friends.
What's worrying to me about this potential acquisition is that it will concentrate too much power with one entity, and that can't be good. This is a development that has been going on for a while now, the FOSS community made the mistake to place too much trust in GitHub for a long time.
GitLab is different that way. It's still a for-profit company behind it, but the client is open-source. You can even host it yourself, and even though real federation is not there yet, it's a lot more likely to come.
The biggest problem GitLab has at the moment is that it's a lot smaller than GitHub. GitHub has 27 million users and 49 million repositories, [GitLab only has 100.000 users/groups (even though that number seems to be pretty old). When we moved UBports from Launchpad to GitHub a little more than a year ago, we discussed GitLab as an option as well, but dismissed it because of lack of adoption. Since then, Gnome has proven that it's possible to move a big open source project to GitLab, and it worked for them.
All in all, i have to say i'm in favor of moving, but i would not rush things. The migration itself is pretty straightforward thanks to great tools, but there's a lot of stuff around it that needs to be modified. Most work will probably be updating the documentation and workflows. Worth it, but no need to rush it. We could make some preparations now, really analyze what to look out for, and make the move after OTA-4.
And for the lack of users, build it and he will come i guess ;)