I opened the forum today, and I thought "The very first post I will encounter will be about Microsoft buying GitHub"... It didn't fail!
My opinion is that there is no reason to hurry or panic. Who knows, microsoft is serious about their new love for open-source.. I have my doubts but let's give them a chance to prove themselves and keep a close eye on what they are doing. I like their new CEO, let's see...
In any case, we moved out of Sourceforge once already, and since then, we decided never to hook ourselves to a specific platform again. We always thought this could happen with Github or any other platform too. So if we need to move the FreeCAD source code somewhere else tomorrow, there is virtually no difficulty. We don't depend on them, the FreeCAD source code doesn't depend on them and is safely duplicated on hundreds of computers thanks to git, we are just hosting our "public" source code address there.
But let's be vigilant!