Somewhat related, part of me wonders if Rotondo is working on Left 4 Block again but with the new default AI.
I remember a while ago, back before v19, someone said he was going to update it, but he was waiting for a certain update. Well we got the launcher with v19, along with v21 we got gamemodes, and now with the recent revision we have default AI. I think it's only a matter of time before he updates it or releases a new one.