You do not infringe on rights of the licensee, licensee may continue to use the licensed IP, there was no damage inflicted. I believe there's no form of "license to sue" (besides legal representation which is a different thing).
It's in the field of copyright rather than patents, but the Righthaven suits suggest some form of precedent in this area.
But that's kind of a sideshow - I believe the real issue being pointed at is if the defendant chooses to argue that a patent is invalid, and succeeds, then the only award they get is the now-invalidated patent.
Needless to say, IANAL as well.