Eliot Shorr-Parks of NJ.com is reporting that the Titans were one of 3 teams that expressed interest in trading for Nick Foles back in January at the Senior Bowl (Rams and Texans were the other two) From the linked article:
With head coach Chip Kelly, the coaching staff and front office executives in Mobile, Ala. for the Senior Bowl in January, the team made an effort to gauge the value of Foles with other teams in the league.....
Three teams that were interested in Foles at the time, per a person with knowledge of the situation who requested anonymity, were the St. Louis Rams, Tennessee Titans and Houston Texans.
The Texans would presumably be out now that they have reportedly signed both Brian Hoyer and Ryan Mallett.
If you will allow me to speculate here, my guess is that any package between the Eagles and Titans that included Foles would also have to include the #2 overall pick because Chip Kelly wants Marcus Mariota (also speculating that Kelly isn't planning on just giving the keys to Mark Sanchez). Since the Titans have the second pick, they should be the most attractive team to the Eagles.
Foles is a nice player, and would be an ideal guy to have in camp to battle Zach Mettenberger for the starting job, but if the Titans are going to make a deal, they better still get a bunch of picks to move all the way back to #20 in the draft. For me, it would need to include AT LEAST this year's 2, 3 and 4 and next year's 1 and 3.
All of this is speculation at this point, but with everything the Titans need, it would be a good idea for them to explore this option.