I'm going to get hate for this, but.....
they should have Lesnar defend the WWE Championship (or whatever it's become called by that point) against Roman Reigns at Mania 32.
As you suggest, Lesnar should be kept out of the title picture until late 2015 and so should Reigns (he needs seasoning anyway). Have Reigns win the Rumble in 2016 and those two face off for the title in that match (maybe even put Rocky or Undertaker in Reigns' corner....something like that).
wk
Expects hate, gets three likes. 1: Was about to rip you for your misconception but then realized you weren't Aids. I'll never get used to that avatar, no matter how perfect it is.
Could they do that with Lesnar all the way to WM32? Absolutely. He'll work Summerslam, 3 shows next year, then probably the 2016 Rumble. Not too much to ask for him to go 5-0, and at this point a competitive match with Lesnar will help someone more than virtually anything else (ask CM Punk). The difficult thing will be with Reigns. I wonder if they can roll with the Shield for another year (sounds good to me!) to kinda hide Reigns, then slowly push him + a couple of other guys leading up to WM32. Roman Reigns is still unproven, so I'd have my doubts about writing his name in pen to receive such a massive accolade.
Either way, they'll probably make enough new stars this year (I hope lease to give Reigns enough interesting feuds to last throughout 2015 if they want to go that way.