Personally, I'd enjoy seeing Cena turn heel and beat the crap out of 'Taker and end his WM streak. It would be the biggest heal-turn and negative crowd reaction since Hogan turned heal at WCW Bash at the Beach 1996. Might even see almost as much trash throw in the ring as they did that night as well.
If Cena is the one who ends the streak that just might be enough to make me stop watching WWE forever.
Now, on Taker fueds I'd like to see.
John Cena vs. Undertaker- I think this would be good but I don't think Cena will ever turn heel, I guess they could do it face vs. face. Or, hear is a possbility, turn Taker heel. He could go back to the Attitude Era Lord of Darkness thing. It could possibly work. But Cena absolutely cannot go over taker at Mania. But other than that it's be a good fued.
Jack Swagger vs. Undertaker- I would love to see this fued. I think Swagger could pull it off, it would be kind of like Taker vs. Lesnar, and they could have some great matches. I'd love to see it.
Undertaker vs. Carlito- Carlito is going to turn on Primo from what I've heard, so I'd like to see Carlito or Taker switch brands and this could be a great way to push Carlito into the Main Event scene. It could start by Carlito coming out and saying, something like, you know that I don't like cool, and someone who really isn't cool is Undertaker. He buries people alive, he cruicfies them, he sends them to hell, he's a devil worshipper, that's definitley not cool. As a matter of fact, this could work on a redebuting Carlito's Cabana with taker as the guest, and then he could spit an apple in Taker's face, and Taker could go psycho on him and it would start a fued. I could see Carlito cheating to go over on Taker, then maybe forcing a countout to win the match, then ends up in Long setting up a Hell in a Cell or Steel Cage match to end the fued, with so no one can get in, there's no way to cheat, and there is no way to get count outs. I really think these guys could put on some good matches and it would further Carlito.
The Miz vs. Undertaker- I think these guys would put on good matches and I doubt Taker would bury The Miz like Cena did. This could really further The Miz's career greatly. It could start with The Miz coming out on RAW and calling Taker and Taker not showing, so Miz is "1-0". Then Miz shows up on Smackdown and call's him out. Taker doesn't show on his home show so now Miz is "2-0", "1-0" on taker's home turf. So next Smackdown Miz calls him out and when he doesn't show, Miz starts to declare himself "3-0" but before he can the lights go out there is some staticy white noise crap on the PA and static picture flashes on the titantron. Lets say Miz wins the IC title in an open challenge at breaking point, and the next night is when he starts the call outs. Then the next week Miz is in a match against someone and if they win they get a title shot and during the match the lights go out, and purple lights come on and lightning strikes the top of the ramp or something and Miz gets beat on a schoolboy pin. Now at HIAC (*sigh* stupid) The lgihts go out and Miz loses his title, setting up a match at Annihlation against taker (voted for if it keeps the Cyber Sunday format, it's just booked regular if not) and Miz brings out a fake Taker like DiBiase did once and beats him. So now at SS we have Taker's return (I know it's supposed to be by Summerslam but still) in a SS Tag match 5 on 5 Taker's team vs. Miz's. It could be Taker's Ministry (Kane, Goldust, maybe Hawkins in a new gimmick, maybe Jeff Hardy if he's out of the main event and Taker) vs. Miz and his Mizfits, whatever team he comes up with. So Miz's team can pull the upset by cheating. So this sets up Miz/Taker in a casket match (HIAC PPV was would have just happened so no HIAC) which Taker wins, ending the fued.
B.O.D. vs. Team Extreme vs. Edge/Jericho- So Edge and jericho have the titles. They can work there way through the Tag Division and claim they have no more competition left. They issue an open challenge for Summerslam. The weeks up to the PPV show Jeff Hardy talking to someone on a cell phone, but it is not revealed what they are talking about or who he is talking to. So at SummerSlam Edge/Jericho await there opponets when The Hardyz music hits, revealing Matt is who Jeff was talking to all those weeks, and they've reconciled. Before the match starts Teddy Long announces another team wants to accpet the open challenge, and this will now be a triple-threat tag team contest. The fans are puzzled but then the gong tolls followed by the lights going out with the intro to Kanes music playing. It hits it's peak and breaks back into Taker's music while Taker and Kane walk to the ring together, fire explosions on each side of the ramp, like Taker did at WM 24. This starts a fued culminating in a TLC match, which would be epic.