In general, all rights revert to everyone who holds a termination interest -- the creator(s) (or, where relevant, their heirs), whether or not the holder signed the termination notice.
Exception: Rights to derivative works already created before termination are not affected by the termination. For example, if you granted film rights in your novel, and the film was made before you terminated, the producer can continue to exploit the film as before.
“A derivative work prepared under authority of the grant before its termination may continue to be utilized under the terms of the grant after its termination …” -- 17 U.S.C. § 203(b)(1)
Scope of the exception: The exception does not extend to new derivative works (including remakes of already-made derivative works) For example, if you granted film rights in your novel, and one film was made before you terminated, the producer cannot now make sequels or other new adaptations, though it can continue to exploit the original film. “ … but this privilege does not extend to the preparation after the termination of other derivative works based upon the copyrighted work covered by the grant” -- 17 U.S.C. § 203(b)(1)
