There are projects of mine where I'm the only relevant core contributor but the ecosystem is developed by many other people and it's largely worked out fine.
I would hope that if either of us got hit by the proverbial bus that people involved in the ecosystem would pour themselves a strong drink and dig in to the necessary maintenance anyway.
Projects I've ended up moving on from have regularly worked out that way, and I think that while solid might not be as popular as some people would want for something to bet their production code on, it does seem to me that it's popular -enough- that I don't believe you're a truly dangerous single point of failure here.
(if this comment read as negative rather than an attempt at a clear eyed analysis, I apologise for phrasing it wrong)