Eventually it will end up on Gutenberg, no doubt. But I have no idea how long that will take--I mean, now that the public domain has started rolling forward in the US, I'm sure Gutenberg has its hands full with the new works, and I don't know how they choose what to work on, either.

This is why I just ordered myself a first edition of Flight of the Heron (for only $6.98!) so that I can read from that when I record it for Librivox. For newer editions, there's a complicated process to make sure the new edition doesn't have a newer copyright.