Prospect rankings are going to change a bit over the next few months. Players who weren't even on the radar will become surefire first-rounders, and surefire first-rounders will drop to Day 3 of the draft.
Still, big risers and free-fallers are the exception, not the rule, and most of the prospects will stay ranked close to where they are now throughout the process; so even this far out, mock drafts can be fairly reliable.
The Tennessee Titans are lucky to have a lot of their needs match up with deep, talented groups of prospects, so they could end up with some very good players, if they get lucky.
Of course, a new regime could mean a lot of new things when it comes to the draft, so anything could happen. Here is an ideal mock draft for the Titans as things stand now.