Peyton Manning's recovery process hasn't been going as well as hoped and could result in the star quarterback missing the entire 2012-13 season.

Yahoo Sports reported on Monday that the nerves in Manning's arm are not healing as quickly as hoped and don't appear to be progressing at enough of a rate to indicate he will play again.

Manning underwent a spinal fusion surgery in August, which has healed as expected, but he hasn't been able to gain back the velocity that made him one of the most dominant quarterbacks in the entire NFL.

The four-time MVP is working his hardest to return to the field, but sources around the league continue to doubt whether he will be ready to play this season - or ever again. Sports Illustrated's Peter King wrote in his Monday Morning QB column that Gil Brandt, a long-time friend of the Manning family, told him that we've probably seen the last of Peyton.

The latest reports about the possible end of Manning's NFL career add some credence to actor Rob Lowe's tweets two weeks ago. The Parks and Recreation star tweeted on Jan. 18th, Hearing my fave, #18 Peyton Manning will not return to #NFL. Wow. #Colts.

The tweet was quickly denied by Manning's agent, Tom Condon, and his father, Archie Manning, but perhaps Lowe did have some inside information about Manning's situation. Lowe is reportedly very close with Irsay and might have known that Manning's rehab wasn't going as well as hoped.

Manning laughed off Sodapop Curtis -- a role Lowe had in the 1980s movie The Outsiders -- announcing his retirement, but it's clear that his future in the NFL isn't a certainty. At the very least, according to Yahoo, most won't know for sure about Manning's status until the summer.

Right now, Peyton is at about six months, a league-affiliated doctor, who hadn't seen Manning, told Yahoo Sports.  He should have a much better idea by July or August just how far he's going to get ... even then, that's only a part of it. You can tell about 80 percent of how the nerves and the muscles are healing by rehab. What you really have to see is how his arm holds up when he starts to throw. Does he have the same velocity on the 15-yard out? Can he throw the 60-yard pass? Can he throw for 30 minutes before his arm gets tired? Can he throw for an hour? It's a very complicated process.

The latest news likely makes it an even easier decision for the Colts to release their franchise quarterback. The Colts have until March 1st to release Manning before they have to pay him a $28 million roster bonus -- leading many to believe Colts owner Jim Irsay has already made up his mind to release the quarterback.

Irsay has denied that he has already made up his mind about what to do with Manning, but the NFL Network reported last week that sources around the league expected the Colts to release him before the NFL Combine begins on Feb. 22nd.

The Washington Redskins, Miami Dolphins, Arizona Cardinals, San Francisco 49ers, and New York Jets have all been mentioned as possible landing spots for Manning, but it will all depend on his health. The combination of Manning's desire to stay in Indianapolis with rehabilitation delays could cause the future Hall of Famer to retire from the NFL.

The decision would likely be an extremely tough one for the ultra-competitive Manning, but he should take solace in knowing he has a bright future in another career.

Esquire recently named Peyton Manning as the No. 1 current NFL player that you will see on television.

If I were to rank the top five active players that I'd want on a studio show, Peyton Manning would be number one, number two, number three, number four, and number five, an unnamed television executive told the men's magazine.

One media reporter even speculated that he'll be the most sought after ex-player to entire the media world, possibly ever.