All of this is based on assumption that Deron keeps his mouth shut and suddenly becomes a model citizen.
The problem with these LeBron, Melo, Howard, Williams situations is that the moment a star starts pouting, all long-term planning goes out the window. It becomes all about making moves right now to keep him happy. You can't ask him to wait 2 years so you can clear cap space, because he's a "fierce competitor" or "extremely driven" or whatever other euphemism for "unearned sense of entitlement" you want. Then you get Cleveland signing Jamison and Shaq's corpse, Magic and Arenas, Hedo being reacquired, Iverson to Nuggets, then Billups to Nuggets, etc.
Had Deron stayed, the Jazz FO would have been much more likely to pull some boneheaded move to get him "help now."