Really imagine this as a triple main event:
Triple H vs. Brock Lesnar
WWE Title: CM Punk vs. John Cena
World Heavyweight Title: Sheamus vs. Randy Orton
I've said this before and I'm sure I'll say it many times again, but HHH/Lesnar is the perfect match for SummerSlam. This event has been missing that huge dream match that made it so special, and such an awesome companion piece to WrestleMania. The last event to really have a big dream match was 2008--Cena/Batista. Before that you had Cena/Orton, Orton/Hogan, Flair/Foley, Hogan/HBK, (2003 would have had HHH/Goldberg were it not for HHH's injury), 2002 had HBK/HHH and Rock/Lesnar, 2001 had Booker/Rock, and so on.
This is a huge match that has never happened, that has loads of potential. If Cena can be in an intense brawl with Lesnar, HHH...forget about it. I agree that this should get a NHB stip...just let it go crazy.
I have a feeling they may do Punk/Cena again at MITB to commemorate their epic first PPV match, or they do it at SummerSlam, since SS is also a good place where huge rivalries pick up again (Cena/Orton, UT/Edge, Rey/Chavo, Cena/Edge, UT/Orton, Eddie/Angle, Lesnar/Angle).
Since Punk would still be champion, it would be huge. Punk defending the title after being champ for 10 months, against a guy he's never lost to (on ppv). Only problem is, I wouldn't want Cena to be the guy to end Punk's title reign, so this really only works if Punk retains and moves on. Still, this could be an amazing co main event.
And as I mentioned before, Sheamus/Orton have amazing chemistry. All their matches in 2010/2011 have been fast-paced, powerful brawls, and a lot of fun. Seeing them clash as babyfaces for the first time ever, as strange as it sounds, is kind of dream match for me.
This could be the best SummerSlam in a while.