We all extended our contracts for two years to preserve our bonus minutes, AND got new phones. I agree that Cingular will cause, one way or another, everyone to migrate to their system, although I think it would be easier to merge the systems (as it appears that they did with their accounting systems).
Bottom line, there is a level of support necessary to fulfill the contracts, from the carriers' side, and it appears that they are trying to circumvent that support. There can be no complaints regarding breach of contract if you have a new contract.
Cingular's advertising says effectively, that a customer need make no changes unless the customer wants roll over minutes... that is proving to not be the case.