Edge will be returning in November, not October. Smackdown is low on talent as it is. As of now, they only have The Undertaker and Edge. These two are set for one of the best Wrestlemania matches of all time in my opinion. The WWE wouldn't ruin that to move Edge to Raw for a short DX feud.
I have changed my mind a few times with this match. If he does return, I can't see Jericho feuding with Cena while he has the championship. When HBK returns, I can't see him feuding with Randy Orton while he is champ. I see this match ending in a double count out, again. The only person I can see taking the belt off of Cena is Triple H. That would set up a great Kennedy-Triple H feud for the WWE Championship. After Jericho, Orton, Cena and HBK are finished with their feuds, they can move on to the WWE title