You're extrapolating like 2 seasons ahead here but that's a reasonable example. Alternatively though we could possibly trade Landry/Casspi/Garcia/Dalembert's awesome expiring for Carmelo. Go 50-32, make the playoffs, advance to the 2nd round and save our team. Who knows really?
Well, 1 season ahead really.
As far as your alternative trade scenario goes, nobody nobody nobody nobody here would say no to it if it came with a Carmelo extension and probably most people would take it even if it didn't (and despite the fact that we still wouldn't have a good chance to make the playoffs at this point or even keep him next season). But it's a complete no-go from the Nuggets' point of view. They want multiple first-round picks and a young superstar in the making. You're offering a useful utility player with a long contract, a young kid without superstar potential, and two junky expirings. The Nuggets, in the parlance of the board, hang up.