The Titans have a solid linebacking core. Keith Bulluck had his lowest tackle number (88) since before he became a starter, but that is because the rest of the defense played so well not because his skills are slipping. David Thornton had a great year with 122 tackles. The Titans also got solid play from Ryan Fowler and Stephen Tulloch from the middle linebacker spot.
The Titans will not be looking for any starting help during this offseason at linebacker. They will be looking for some depth help however. The only other quality linebacker they have on the roster currently is Gilbert Gardner who is a free agent. The Titans should be able to get him back for a reasonable price, but they will still need to add a guy or two, not just for depth purposes but special teams as well.
Linebacker may be the spot where the Titans are the most solid when it comes to the starters. They will add a guy to this unit either late in the draft or in free agency.