My plan wouldn't change - keep driving my '05. I figure as long as I stay on top of the maintenance it'll keep on going. These things are so well built that I don't see a real reason to get something else unless I total it...and, right now at least, I'd just buy another one. If something comes out down the road that really grabs me I might consider something else, but nothing out there makes me want to "jump ship" right now.
If mine was totalled and I couldn't replace it with another T4R, I'd probably go back to an F150. I had a 2008 FX4 S-Crew before my T4R, and I do miss it sometimes.