Hard to say. L.A. obviously isn't working for the Chargers.
However, Stan would have to let them out of their lease agreement as well as negotiate any loans he's made which use that sublease as collateral. I'm reasonably sure he'd do this if it meant L.A. all to himself.
The Owners would have to agree to forgive the multiple millions in re-location fees they are owed by the Chargers. It's what would be best for the league, but what might not be best for the individual Owner. Then again, they might still get that as part of a re-re-location.
The Raiders have to be settled in Las Vegas or they might still invoke their option to be the second team in L.A.
I don't think San Antonio is out of the picture entirely either.