unfortunately adwords expert Jim Banks is currently on vacation in Canada, otherwise we would have got the facts very quickly.
Personally I think it will NOT happen anytime soon, maybe in 9>12 mths time.
I think they will have their hands full with the premium listings going to Adwords, along with past experience of Overture and Espotting.
Google adwords unlike the others was basically built on the 1man band business and I am sure they will realise that you do not want to piss these people off.
I wish there was some definite answer, but I doubt anyone apart from a few at the very top know whats happening.
interesting question though, one which has gone through my mind many a time.