I wouldn't mind that trade unless they give up something stupid like a 3rd round draft pick or higher. He's older yes but there are plenty of productive older, big WR's like him (Andre Johnson, Boldin). He'll lose speed but who cares, he wasn't fast to begin with.
Going to hook here but I really think a new O line coach would help a lot. There's enough 1/2nd round picks to assume that there is enough talent. The problem is execution (procedure penalties, holding, missed blocks), which falls on the coach. Cable is more concerned with his guys being tough brawlers and I just don't think he has any idea how to coach any sort of technique.
TLDR; Carroll should pull a Harbaugh and fire Cable (and Bevell?) and make another SB run?