CDs are duration deposits, but you can still get the money out minus some fees associated with the early withdrawal. That doesn't help the run on the bank situation.
So long as the bank has reserves (out of profits) they can offer to buy people out early, according to their own profit and loss calculations. But they can't be compelled to, and they must have that money available to them at the given moment.
In this make believe banking system that I am making up. :)