I think Melo has the best chance of being bought out before the season. Wade is more of a mid season buy out candidate. Wade will sell tickets and until one of their young guy emerges, Wade will be the selling point to come to Bulls games.
Neither is a sure bet to join the Cavs. Wade could look to set up his next contract like Joe Johnson did. Melo has said he wants to stay close to his family, is Cleveland close enough to NYC. What if his wife gets a job offer in L.A. and he decides to join the clippers.
I think the Cavs have to be aggressive with going to get Melo. Trade always Frye, Shump, and RJ to the Knicks for Melo. If they can move any of those guys off to other teams who missed out on free agents and get assets back, the front office should do it. I think the Knicks would take anyone on one year contracts to possibly move later than to just buy out Melo. If they buy him out they also take the cap hit for his player option next year.