Why do you think Turner has FA bust written all over him? Have you even seen him play? Green and Turner's situation are nothing alike. Green came here with alot of wear and tear and coming off a serious knee injury. Turner happens to play behind the best RB in the game and all he does is produce. He is injury free with limited wear and tear. They are nothing alike at all. You have no idea what you are talking about.
Look I am not saying Turner is going to be the next Earl, but he clearly has skills. He may have a hard time finding big $$$ because of all the young RBs in the draft - D-Mac, Ray Rice, HArt, Mendenhall, Stewart, Jones, ect....
If we can add other positions of need then I say do it - get as many pieces as possible. he gets a stupid offer from another team then they can have him, but I don't think that will be the case. Cut AG, and use some of the saving to replace him with a younger alternative and address DB and OL in the draft. If we did not have so many needs then I wouldn't want to sign Turner because we could find a good back for cheaper in the draft, BUT we have LOTS of holes - signing him (provided the contract will work for us) and filling other needs trhough the draft gets us closer to where we want to be - a winning team.