There are two narratives for what's going on in Bronco-land right now.
One is that the 39 year old quarterback who was blowing the doors off the league early in the season got hurt but didn't come off the field. He spent the last 5 weeks of the season and the playoff round playing on a quad with less structural integrity than Paul Broun's understanding of The Origin of the Species, and for a precision passer like Manning that's death.
Without Peyton being Peyton and threading balls through six-inch-wide gaps in the coverage so that his receivers could make catches in stride, the Denver offense sputtered, which left the defense on the field too long, and the end result is that Indy is going off to get slaughtered by the Patriots in the AFC Championship game.
Alternately, John Fox - a man who ran up 4 wins in 4 seasons in Denver, took a team with Tim Tebow as QB to the playoffs and took a team with Jake Delhomme (and a roided-up punter) to the Super Bowl - botched all the talent that GM John Elway had acquired on both sides of the ball. Thus, he and his staff were to blame for the loss, and needed to be purged like Trotskyites in Stalin's Kremlin.
And so, with Fox out and the sports talk airwaves a-flutter with talk of The Demise Of Peyton (hint: he'll be back and he'll be fine once his quad heals), we get hints of the real dynamic in Denver. Theoretically Elway + Peyton should be a match made in heaven, but as the years tick by and no rings accrue, it becomes faintly apparent that there's really room for only one savior QB in the Mile High City. Maybe, as some sources suggest, it was Manning who organized his coach's ouster, but that doesn't make a lot of sense. Why get rid of the guy who let him do whatever he wanted to do and largely stuck to the defensive side of the ball? On the other hand, if Elway deep down doesn't want there to be another quarterback as beloved in Denver as he is - and as much as Denver loves Elway, they don't love him as much as he seems to love himself - then maybe asking Manning to come back off that bum quad with a new coach beholden to Elway (say, Elway's former backup) and a new system and a significantly turned-over roster is a way of making sure that Captain Omaha never gets to be quite the hero Elway was.
Then of course a new QB, hand-selected by Elway without the legend or baggage of Manning comes in, and all his glory is owed, at least a little bit, to #7.
Is it far-fetched? Sure. But it's a long way to the next Bronco's game, and it makes as least as much sense as the frantic Manning-forgot-how-to-play-QB nonsense going around right now.