That a large chunk of this knowledge appears to have been offloaded into a test suite is good, and does a lot to combat this, but obviously nothing is quite as good as experience and skill and knowledge about the specifics of the code in question.

As a theoretical situation, how much more likely is a fork to eventually succeed if one or more of the code SQLite developers is no longer available to contribute to SQLite? There are a lot of variables that go into that, but I would feel comfortable saying "more likely than if those developers were still present". That idea encapsulates some of the harm I was thinking of.