A big gamble. Any good GM wouldn't make that gamble. There's maybe 20-30 people on Raw and now, 3 picks left to be made. Can you realistically tell me that the odds of the World Champion being drafted are good enough to allow said gamble? No.
I'm not saying that they won't put the World Champion on Smackdown, but in kayfabe I don't see how Long could be comfortable with this situation. If I was the GM, I'd be on the phone right now either trying to get Cena back or setting up a post-Vengeance trade for the winner of HHH/Batista, because hey, if I get the champion for free without using a pick on him, I could get someone else real good like a Shelton or a Jericho.