I don't think it's unlikely at all. Git might be succeeded by something, but certainly some projects will be around.<p>For example, the Emacs repository (the git clone at least. I haven't checked bzr) has commits dated before my birth. Some of the history is certainly lost due to lossy conversion. RCS and CVS never were very good at tracking it anyway. However, any conversion from git is going to have to retain full history. (why would you convert to something inferior?)<p>Furthermore, as git is distributed, the history of a project is fully contained within countless clones. I doubt any sufficiently popular open source project could just disappear from the internet. That's why the hosting sites don't matter either. If one goes down, it's trivial to migrate to another host.