I do believe the Colts at some point will release or try to trade Peyton Manning.
If that was to happen the Cardinals make the most sense if you are Manning. Mainly because of Larry Fitzgerald and a passing system that worked well with another aging quarterback Kurt Warner.
I still have my doubts after taking a year off and three neck surgeries he will ever be the Peyton of old, but at the right price you have to take a chance that he is.