I use github a lot but I'm not too worried about the vendor lock-in. Since git is by nature distributed it's trivial to migrate the code elsewhere. The real problem is migrating the issues (but there are solutions for that as well, even if it's a bit more clunky) and the "social network" aspect but I don't care much for that myself.

But you're right, maybe IPFS plus something like Fossil (including issues in the VCS directly) could be a good solution to have a truly decentralized "platform".