IMO, Downs is probably the biggest trade chip we have right now. A lefty reliever is something that contenders will be looking for.
Also, you have to look at how the team is contructed. Pujols and Hamilton are not going anywhere. Trout can yield us pretty much an entire farm system, but chances are, unless he shows that he will absolutely not re-sign with the Angels, he's not going to be moved.
Shuck is not a starting outfielder. He would be better off on the bench. Same with Cowgill. So that's at least some bench depth. That leaves Bourjos and Calhoun. having one as bench depth would be nice. But if one had to go, I would think teams would give more for Calhoun. Just because he has 6 years of control left, where Bourjos is entering into expensive arbitration years.
Trumbo is not going to be traded, because Pujols can't play the field. There is no one else that can play firstbase on a regular basis. This is a lack of depth issue. Which brings us to 2b, SS and 3B. Again, lack of depth leads us to them being on the not going to be traded list.
As for starting pitching. Seeing as what Texas just paid for a rental starter, you keep everything you have. Except for maybe Blanton. But who would trade for him anyways? You try to re-sign Vargas, and you also keep Hanson. That would put 4 in the rotation, and the last spot between Williams and Richards, and since we can't get rid of him, Blanton. You also have to consider that starting pitching is just horrible this offseason in regards to free agents. So filling a hole will be difficult.
Except for a few relievers, I don't see much changing between now and next season.