GitHub has been insanity since it was acquired by Microsoft. The most widespread alternative that I know of is GitLab which has an inbuilt migration feature. Core should have moved a long time ago, however it's a tricky thing.. you just abandon the GitHub? how do you proceed exactly? how do you get people on board?
GitLab is almost the same as GitHub, so I don't see what substantial change are we going to have from that. I know there had been a lot of discussions in reddit, here in this forum and some bitcoin IRC channels regarding the migration but the end result is always the same: where do we go from here? Now I know Microsoft hasn't been that friendly to people, especially projects and accounts coming in from affected countries of the trade bans, but then again I don't see anything that they have been doing recently to cause a concern to move the whole project elsewhere--or at least I'm not fully informed of what's happening deep within the surface.
It's a compromise developers have to deal with in their pursuit to maintain bitcoin's code intact and up-to-date. Not everybody likes it but it
has to be there somehow as it's the only trusted repo we have right now.
I don't think a decentralized solution exists, or even is possible. You need to have somewhere for people to submit issues, patches, and comments, how would you decentralize that.
--
Then there are self hosted solutions. The problem with this is that there is no formal organization that backs Bitcoin Core. In order for a self hosted solution to work, someone would have to pay for servers and set it up themselves. They would basically have to run it using their own money and deal with things like DDoS attacks, server management, etc. That's a huge undertaking in both effort and cost. Then there's also the bus factor: what happens if that person gets hit by a bus? So in general, self hosted solutions aren't really a solution for us.
With your analogy, I remember what happened to QuadrigaCX's funds. Change this scenario into someone managing a self-hosted repo whcih everybody used, until such time that this dude dies unexpectedly without anyone knowing until the whole system shuts down/certs expired etc etc. Self-hosting is a no-go, but if there's such an organization with no political interest whatsoever and only wants bitcoin to move forward and are willing to pay for such (I highly doubt this), go ahead and migrate, although of course, the community still needs to decide on where to go from there. A simple problem yet leads to branches of even more problems, as if we are onto a stalemate and can't move no further, unless of course MS goes full retard and do something that everyone will not like.