I think his career can go one of two ways. He may be expected to carry the load and just whittle away like Eddie George, or he can play a situational role like Bettis or Dillon and have a nice finish to his career. If he stays in Seattle, and they draft/sign a RB that can carry the load, I could easily see him being a 500-600 yard 8-10 TD guy. If they do not and go with him and Morris, think E. George.
If the Hawks release him, it will obviously depend on where he lands. I think teams like the Bears, Jets, Miami, and the Pats (sneaky play) could use him in a situational role.
basically, if he wants to end on a high note, he better pray he gets released.