If someone calls and asks about Trumbo, you really have to listen to their offer. His salary in the coming years will certainly go up, but he's not going to break the bank, so keeping or trading him because of salary shouldn't even be on anyone's radar.
There are too many times when he looks completely baffled by some of the pitches, and his swings are embarrassing to watch. He's back on his heals or he swings only with his arms. He's a known quantity, but he is what he is. If someone offers a reasonable player in return, listen carefully.