Conventional wisdom told us that Dave Batista v. John Cena would headline WrestleMania XXV in Houston.  Cena himself even teased idea during an episode of "Monday Night Raw" a few weeks ago.

But that match is not going to wait for the granddaddy of them all in April.  No, we get it this Sunday at SummerSlam '08.

Of course, this is the same conventional wisdom that lead us all to believe that 'Mania would be headlined by the Cena/Triple H rematch from WrestleMania XXII.  That was until the two locked up for Night of Champions back in June.  They may not be Austin/Rock, but they're still the two biggest names in the business right now.

And that leaves fans, and those who like to speculate about such things, scratching their heads.  What is going to be the main event for WrestleMania XXV?

It could have been Edge v. Triple H for the WWE Championship.  In fact, that where I thought things would lead the moment Trips was drafted to SmackDown.  But, nope, that match took place at the Great American Bash.

It seemed to only leave some permutation of Batista and Cena, but this SummerSlam match has torpedoed even that.  So, what on earth could it be?

Here's some speculation:

1. Triple H v. Undertaker

It seems to make sense.  Sure, the two locked up at WrestleMania XVII, but that was when 'Taker was wearing his American Badass image, and Triple H was hotly embroiled in the McMahon-Helmsley Era.  Visually it would be something different.  And if the seven-year rule in pro wrestling is to be believed, it would be fresh.

Plus, both these performers are synonymous with WrestleMania.  Undertaker's streak of course has been a main selling point for the big show for years.  And Triple H has headlined five of the past nine Mania's.  The ones he wasn't headlining, he was competing for a world title, right under the main event, or hurt and originally slated for the top spot anyway.

The problem with this match is the question of who wins.  Does 'Taker's streak go down in his hometown?  Would this be the Dead Man's last WrestleMania?  There's no need for Undertaker to be put over ala Cena and Batista.  On the other hand, it seems a bit of a letdown to see the streak fall to Triple H, but all these factors would keep fans guessing. 

2. Dave Batista v. John Cena, the rematch...in a steel cage!

How long has it been since there was a steel cage during WrestleMania?  Well, it's been 22 years.  King Kong Bundy vied for Hulk Hogan's WWE Championship in the big blue steel cage during WrestleMania II, the part of the show that came from the Los Angeles Memorial Sports Arena. 

Now that WWE already uncorked the genie's bottle that is Batista/Cena, why not have them get it on again behind the fence?  When I first heard the rumblings of a potential Batista/Cena main event, I wasn't pleased.  Sure, Cena has improved dramatically over the past few years, but the quality of his matches highly dependent on who he's paired with.  Batista is...well, Batista.

But they're both brawlers and can both make a match look brutal.  It would make sense to let them go at behind the steel.  It might up the ante a bit.

However, I see no way that Cena could not win this one to close WrestleMania.  Take that as a promise or a threat

3. John Cena v. CM Punk

Don't count out CM Punk as a potential dynamo as the company moves forward.  Sure, he's booked now as the underdog clutching the championship, but if WWE can get past that and learn from the mistakes of Rey Mysterio's championship run, Punk could be a force to reckoned with for years to come. 

Who'd be heel?  Punk can heel out with the best of them and would make an excellent foil for Cena's clean-cut image.  It could also run as face v. face match with much less heat.  Or, could we see -gasp- John Cena turn heel to steal the World Heavyweight Championship from Punk?

Try this on for size.  Punk does lose the World Heavyweight Championship at some point in the near future.  Somehow the title drifts over to Cena.  What if Punk were to win the Royal Rumble and get a chance to regain his title and prove once and for all he's not a paper champion?  Hmmm...

I'm not Cena's biggest cheerleader, but this is a match I'd plunk down my fifty bucks catch...and then some.

4. Randy Orton v. CM Punk

This is the match I'm waiting for during Punk's World Championship reign.  The storyline possibilities (straight edge versus decadence) are seductive.  The match would be stellar.

If Orton's reinjured collarbone is legitimate, then we won't see him until at least Survivor Series.  If Punk holds onto the title for that period, it's likely we'll see them square off on one of the subsequent pay-per-views.

But what if we didn't?  What if this classic in the making was allowed to fully cook and build to a boil at WrestleMania?  It would certainly turn the page to a new era of WWE.  And it's one I'm frothing to see. 

Of course, it is but a small request to have "Burning In My Light" brought back, but let's not quibble over appetizers when the main course would be this good.

5. Shawn Michaels v. Undertaker

It's an obvious one, but I stick it here anyway.  Pretty much anything Michaels has touched lately turns to wrestling gold.  Look at all the classics he's been in during the past few years: Ric Flair at WrestleMania XXIV, the broadway with John Cena that "Monday Night Raw" from London, the street fight with Vince McMahon at WrestleMania XXII, Hulk Hogan SummerSlam '05, Kurt Angle WrestleMania XXI, the Triple Threat from WrestleMania XX, Chris Jericho WrestleMania XIX, Triple H SummerSlam '02...need I go on...

Neither Michaels nor 'Taker are getting any younger.  One of them might bow out next year.  What send off they'd get with this contest.  You could even throw the WWE Championship into the mix for some added tension. 

Main event or not, this is definitely on my WMXXV wish list.

6. Jeff Hardy v. CM Punk

This is a real dark horse, but again I put it here.  If WWE is really looking for a different course than the direction the ship's been sailing for the past four years, this is the ticket.  Both have rabid fan bases that are only bound to get larger.  If they don't headline WMXXV, could XXVI or XXVII be far behind?

Or course there's also Ken Kennedy and MVP to think about for the future, but I'll eat my tin foil hat if either winds up in this main event.  As the say, however, anything can happen in the WWE.