It's unclear at this point what the final result will be in this situation. A final opinion of this ruling may not be heard for several weeks, which would put it after the draft, and that leaves open the possibility of participating in the supplemental draft for those players involved.
Williams filed a lawsuit of his own today saying the league issued conflicting information about eligibility in the draft which caused him to sacrifice his college career. It's possible that Williams and Clarett could be allowed to return to their college teams in a process that would allow the universities to apply to the NCAA on behalf of the player.
Williams has not contacted USC about that scenario although Carroll said, "We'll continue to help our guy out, just like we did when he was making his decision. Nothing definitive has been declared by the NCAA. Some steps would have to be taken for the players to get back into college football. We don't know yet if this is a permanent situation but it is unfortunate that it continues to turn back and forth for those guys. They don't know where they stand."
When it comes to regaining eligibility there would also be the impact of hiring an agent as well as academic standing. Neither of these issues are clear in terms of how they would be resolved.
information from espn.com was used in this report