It will be interesting what Peyton does. His offensive coordinator is a head coaching candidate for a few teams. Fox gone was basically a riff between he and Elway on control of the roster. Elway wants total control. As for Manning, I think it will depend on who comes in and who they bring in if the OC leaves. He has the weapons to still play his style. Arm strength may be a bit of an issue but he was till better than most QB's in the NFL. They guy is a cerebral quarterback. Similar to what DieYoung is saying. He may not athletically be as good but as many reps as he is taken over the years, he can still beat you. They had some crucial injuries this year and the O-line was inconsistent.
As for Fox, there is some rumors that he could end up with my team-The Bears, but I would wonder if Adam Pace, the new GM (who already said he wants total control of the roster) will work with Fox. I like Fox and he is of the same mold as Bruce Arians, which did a pretty damn good job at turning the Arizona Cardinals around. If not Fox, I would love to see Dave Toub, an ex Bear special teams coach who is in KC now. Guy is fiery and has grit.