I really do hope they're successful in taming Wave's UI complexity and making it actually useful for writing documents collaboratively. Right now Wave is geared towards adding commentary (which it does well), but that isn't very useful if you don't already have a mostly-complete document to mark up. Even with just one editor Wave can be really obnoxious if you try to write something more than a paragraph in one blurb -- it could really use an Etherpad mode!
As someone who's bet on Appjet before, what odds would you give of them pulling that off at Google? By tearing down Etherpad, they've clearly gone all in, but there's a substantial team on multiple continents working on Wave, and they're already set in some rather weird ways that the Appjet guys would have to reform significantly.
Do you understand how their users would be at least apprehensive about this? I should have bought a private copy when I had the chance...
I do have faith that they'll make a splash on the Wave team, but I doubt that they'll be able to fix Wave so that it's a good Etherpad replacement in the next three months.