So assuming that Caldwell gets fired (I'm not sure that he will, but let's just assume), who replaces him? I think it has to be a defensive minded coach because the offense belongs entirely to Peyton (and I refuse to believe that Polian is giving up on his golden boy, especially after the positive medical report he received yesterday). So let's rule out offensive coaches like Jay Gruden, Rob Chudzinski and Russ Grimm (there are two offensive coaches that I will consider but more on that later).
Back to defensive coaches. When I think DC turned head coach, first name that comes to mind is Rob Ryan and I don't think he would mesh well because it will never be his team. It will be Peyton's. Same with other high profile coordinators who either want a shot at head coaching like Mike Zimmer or Mike Pettine or want another chance in the spotlight like Gregg William or Romeo Crennell.
By that same logic, we can rule out the usual suspects of high profile "retired," coaches like Bill Cowher, Jeff Fisher, Jon Gruden, and Brian Bellick. All of these men are far too high in demand to accept a job where they will play second fiddle to a player.
So, here are the names that come to mind for me:
Most Likely - Perry Fewell Perry is a guy who is basically the safe bet. He is a perfectly conventional defensive play caller (which Polian will love). He has a lot more energy and fire than Dungy and Caldwell combined which I think will excite fans but he also doesn't have it in him to really ruffle Peyton's feathers. In other words, he will give the illusion of change while being more of the same. Beyond that, Fewell in recent years has become Mr. Rooney Rule (even more so than Tony Dungy). If you're an owner who has already made up his mind on your next HC and want to interview a minority for the job with no real intention of hiring him, you call Perry Fewell! Having the carrot dangled in front of him for so long has left Fewell hungry. I think he'll accept being Peyton's number two just to get a shot at being HC again. Beyond that, his stock his dropped a lot in the past couple of years so I don't think he'll get a better offer.
Runner-Up - Mike Nolan Granted, he has been a total embarrassment in Miami and his head coach record is abysmal but I think that works in his favor here. He is a guy who can manage a clock and call the defensive plays while Peyton does the rest and he doesn't really have the clout to challenge Peyton. He's a fairly competent as a DC, which is what he would be for all intents and purposes.
Second Runner-up - A no-name One of the new, young, not quite as hot DCs in the league or even position coaches. Carnell Lake has been doing really well in Pittsburgh. Vic Fangio's San Fran defense has done tremendous making him a possibility. Dennis Allen's defense in Denver has been keeping Tebow in games. The advantages to hiring someone like this is that they aren't yet established enough to have any other prospects so they will take the job and fall in line behind Peyton. The downside is, they've not been coordinating very long (if at all) so their experience is limited which could come back to haunt them in issues like handling personnel or clock management. Plus, this is the same way Caldwell got the job. Just a puppet no-name who was hand picked by Peyton and fell apart when Peyton couldn't pull the strings. I don't think the fans will take kindly to that.
Dark Horse 1 - Bruce Arians The first of my dark horses. Arians was Peyton's first professional coach. He is a close friend of the Manning family, so I wouldn't be surprised for him to be one of Peyton's top choices. Beyond that, he has been Roethlisberger's puppet for years, so following a QB's orders is nothing new to him. He doesn't really have any other prospects in the NFL (as he is notorious around the league for ****** play calling). The downside of going this route is that they better have a tremendous DC on hand to fix the mess that is Indy's defense.
Dark Horse 2 - Jim Tressel I've personally wondered if the Colts were bringing Tressel into some no show job in order to prepare for the post-Manning era. Tressel is if nothing else, good with young talent and if they want someone to really groom Luck, you can't find a better offensive mind than Tressel. I think Tressel's recent fallout in the NCAA limits his options (he's won national championships and he's been seriously thrown around as a candidate for Akron...f***ing Akron!). So with so few options and player friendly style, I could see him getting in line behind Manning until it is time to pass the torch at which time he and his new protege Andrew Luck could take the reigns.
Those are my thoughts on the future of the Colts, what are yours?