If the Seahawks don't re-sign Alexander there is zero chance that Edge would be considered. They would consider Lewis but likely only offer a one year deal. What they probably will do is trade up to get Laurence Maroney in the twenties and then sign a veteran back who can share the load. Michael Bennett, Ahman Green, Deshaun Foster, Fred Taylor if he is released, etc. Either way they would likley draft a RB in the first three rounds and pair him with a vet. It would suck for fantasy (although Hasselbeck and the WRs numbers would go up) but the Seahawks would still be in good shape running the ball. I think that's what management has thought all along.
And the whole Carolina debate is really problematic since they would have a tough time giving him any more money than the Seahawks would. Anyway I trully believe that the Seahawks not Alexander are in control of this situation. Both parties know he's a good fit, Alexander's numbers will go down away from Seattle, and although they won't get production from any one player like they did from Alexander, they will still get RBBC production.