As for 'Mania 30 I can agree for Undertaker facing John Cena.
3 main events at Mania
Triple H vs Brock Lesnar
The Rock vs John Cena, for the WWE Championship
CM Punk vs The Undertaker, Respect vs Streak match ^^
I've always had the idea of Taker's final match at Wrestlemania ending in a draw. Here me out. That way someone 'ends the winning streak', but at the same time, Taker remains 'undefeated.' It would keep the amazing Mania allore that no one could ever pin him 1 2 3, but it would put someone over as the guy who got closest. It'd be a wrinkle in his record for sure, but I think it'd be the icing on his legendary career - and a note that he is still human - sooorta.
So it's almost that time for Undertaker to come back and pick his next victim. Taker vs Punk, Rock or Brock has been the talk as of late. Something popped into my head today about Royal Rumble, that could cause the following:
Rock vs Punk for the title, Rock beats Punk and becomes champ. Undertaker is entered in the Rumble and wins. Giving Taker a match vs the champion (Punk, Rock or Cena) at WM. Now follow me here, we've all seen stories that WWE is making a new belt to replace the spinner belt. So what's to stop WWE from having Taker win the title and WM and retire with the belt and the streak in tact. Setting up for WWE to reveal the new WWE belt, then they could hold some type of tournament like they've done in the past and the winner becoming the new WWE undisputed champion.
Now this is a far, far, far cry from happening, but it would be kind of a nice send off for Undertaker.
The worst part of this whole idea is The Deadman retiring with that P.O.S. belt.
WHC > ALL belts please throw that crap spinner belt in the trash can