I feel that this would be an ideal thing for one of the various open source foundations to address. I.e., provide a single-source hosting environment for open source projects without needing to lean on for-profit corporations, which would include some form of hit-by-a-bus solution for those projects that lose a core (or sole) developer.
Trying to piece this stuff together after the fact is always a chore. And no amount of "well, they should have a plan in place" will help. People don't think they're going to die tomorrow, so there's always a reason to put it off for later, so they do.
I don't think anybody's worried about Linux going poof if Linus unexpectantly returns to his home planet, but there are plenty of projects that might have some issues. Having all of the domains, DNS, hosting, etc. somewhere with a real employee that can be contacted to move control to new people if required is a good thing.