I expect Gregg Williams to at least get an interview for the Titans job. Williams was the defensive coordinator for the Oilers/Titans from 1997-2000. That 2000 defense was one of the best in the history of the league and earned him the head coaching job in Buffalo. Williams didn't do so well in Buffalo, putting up a 17-31 record, and was fired after the 2003 season.
Since Williams was fired in Buffalo, he has been the defensive coordinator with the Washington Redskins, Jacksonville Jaguars and currently the New Orleans Saints. He was thought to be the coach in waiting with the Skins, but when Joe Gibbs retired after the 2008 season he was fired instead of getting the job. Some people see this as a red flag, but Daniel Snyder is a wack-job so nothing he does should really mean anything to us.
Williams was almost given the DC job here in 2009, but Bud Adams wouldn't allow to add his son, Blake, to the staff.
I would be all for Gregg Williams getting the job as long as he hired the right offensive coordinator. One of his downfalls in Buffalo was how conservative his offense was. He would need the right guy calling the plays in order to be successful. There would also still be the issue of his son. There is a chance that the Saints think enough of Blake at this point that they wouldn't allow him to move with his dad, but chances are he would still want his son to be a part of the staff. That is against Bud's policies, but I would hope that Adams would be willing to make an exception if Williams is the best guy for the job.