Jake Locker has a shaky future with the Titans that is directly related to having a healthy and successful 2013 with Tennessee. However, even if the Titans have a successful year and end up drafting between 16-22, should they go ahead and pull the trigger on a "back-up" quarterback.
This has nothing to do with Fitzpatrick (he will move to number three on the depth chart) but in a year where at least six quarterbacks have a chance to be legitamate first round values (Bridgewater, Boyd, Fales, Mariota, Hundley, Murray, Manziel, and McCarron) the Titans might be wise to find someone to groom if and when Locker hits his final contract year.
Worst case scenario, the Locker does great over the next two years and tries to charge the Titans a premium since they have another QB on the roster. If that happens then the Titans can use the same money to add other pieces and keep the rookie QB (whoever he is).
Best case Locker has two acceptable years, the Titans draft a capable, mobile QB and they have a Brett Favre-Aaron Rodgers type situation (but probably not with two hall of famers).