Q will probably continue to provide its own implementation of promises so that it can be used for RPC via Q-Connection. ECMAScript and DOM promises may not be suitable for message passing until they produce another iteration on the spec. I do not believe that there is enough political will to push for the RPC cases in the first iteration.
Q will probably adjust footing to align with the new standard interface so we can continue to provide relevant guidance and perhaps serve as a shim.