I don't understand the not a long term fit arguement. Dally isn't old, especially for a pf/c, and nothing he does is based on athleticism. He should be able to do the same things he's done for a decade for at least the next 5 years. A healthy Camby still has a big impact defensively, and he's 37 or 38. Mutumbo was very good defensively into his late 30's.
And as Cousins matures, and gets better, Dally's job becomes easier. Dally is a top priority to resign, no doubt about it. And so what if he falls off a little in 4 years. Cousins will still only be 24 at that point, still not in his prime, but probably a 2 or 3 time all star by that point, and a top 3 center in the league, if not the best. Notice how Dally's impacted the game more , and his numbers improved, during the final couple months after Cousins also improved over his 1st half play, as did their chemistry.