For a definitive answer, you need to double check the contract or agreement. On the face of it, you would seem to still need to provide 3 weeks notice, as long as the provider is still open--as long as it is open, the contract is in force. (Of course, as time passes, once it's going to close in less than 3 weeks, you won't need to provide more notice, as a practical matter, than the amount of time it will remain open.) What may--or even *will*--happen in the future does not affect the present validit or enforceability of a contract. If you need to leave in less than 3 weeks, such as to get an open slot, you may have to accept paying for two providers for some period of time, unfortunately.