I'm a little torn, but this is a real issue. Assuming everyone's healthy, there's really only significant minutes for 4 front court players (sure, a 5th could get spot minutes, but I'd argue that that is almost counter productive). So if the team does hope to move someone like Sully (or anyone else), they should make sure that player isn't playing spot minutes if they hope to get any real trade value.
As for the backcourt, it's also crowded, but I am less worried about that. I do think we'll see our fair share of 3 guard lineups; and quite frankly, I couldn't care less if the rookies don't sniff the floor this season. There's plenty of time for them to develop.
Another thing to consider: while I think the need for Danny to make consolidating trades right now is overrated (just cut PJ 3 or Turner if there are no good deals out there), we do have 3 first rounders and four second rounders next year. At some point, something is going to have to give.