The Rock has already stated that he is going to be doing something at WrestleMania 29. Brock Lesnar is arguably the biggest name that WWE could put in the ring with Rock, and Rock has given some hints about it already, so what better way to market the biggest show of 2013?
As big as that match would be, it should not end up being the main event of the show. There is a long time to go before that show, and a lot of rumored matches are going to change 100 times over. But the biggest potential match that WWE could make is CM Punk vs. "Stone Cold" Steve Austin.
These two have been going back and forth through various media outlets, with the most recent one being an interview with Punk saying that Austin has to be the one to challenge him since he is off "hunting and retired and enjoying his life and doing straight-to-DVD movies."
As big a star as Rock is and as much publicity as the return of Lesnar gave them, Austin's potential return match has to be the main event of the show.
There were some thinking that Austin might return at WrestleMania 28 to do a match with Punk, but it didn't happen thanks in large part to the fact that Rock was already booked on the card and was going to be in the main event.
Austin is a huge star in the wrestling business, even bigger than Rock. He is one of the few legends WWE has not brought back for one final main event run who can get his spotlight back right away on the biggest show of the year.
Rock and Lesnar, if they do wrestle, will find a way to make it great. The crowd in MetLife Stadium on that night would let them know just how big this match is, but as far as the biggest money-making match that would have the fans buzzing, it would be anything involving Austin.
Speculation is going to be running rampant for a long time until we have a definitive word on whether Austin will wrestle or not, but with all these hypothetical scenarios being thrown out there, the best one for WrestleMania 29 would be Rock vs. Brock in the semi-main event and Austin vs. Punk in the main event.