I think the Undertaker and Wyatt are finished, over and done. If Taker shows up to do anymore matches, he won't be beat. If he is then Lesnar's claim of being "the one to beat the one in 21-1" is now null and void. Taker only shows up for Mania now anyway, and if he comes back next year, it will most likely be his last appearance in a WWE ring. He's earned the right to have a long happy life with his family, and I wish him well.
How the hell would that be the case, He said for him to defeat him at SummerSlam. You do realize Taker has been defeated before right? Plenty of times and at SummerSlam before. I don't really get how it makes Lesnar's claim void, if he remains the only man to beat Taker at Mania. Your right he does deserve to win the rest of his matches an just simply retire. But your wrong about it hurting his claim.
But my personal stance on Taker vs Wyatt II? It doesn't need to happen. The first one was decent but wasn't great. If Taker is to wrestle again realistically he is only facing Sting,Cena,or Rollins.
As far as Wyatt's first world title win. I would hold off on that until 2016 or 2017. He doesn't need it. Wyatt already has a special role right now where he stays off TV until he sets his sights on his next target. Before Wyatt gets to the world title he needs to start winning all/majority of those feuds and clean.
I would have Wyatt return to feud with Orton and storyline take him out. In this feud he becomes even darker and a even darker version of his self. No more laughing or smiling. Hell, I would have him be a silent killer. He would only talk when revealing why he is making his target. I know, he is a great talker but his character could benefit alot more from it. Orton would return to get revenge and RKO's him and sets up for a punt when Lesnar's music plays and he gets in his face and points to the Mania sign. This sets up a tweener/face vs tweener/face matchup for Mania.
I would have Wyatt disappear until after Fastlane, where he would return to begin a feud with Triple H. At WrestleMania, I would have him face and defeat Triple H.
His next feud would be John Cena, he goes straight through him clean twice and then win win MITB. He would cash in on the champ and feud with them throughout the summer. The next year Mania, he could face and defeat Brock Lesnar. Yes, I said it. Lesnar will lose at least two more matches in his career. I would have Wyatt be one of those guys. Only people he has really lost to is Cena,Taker and Jericho. Cena has beaten Lesnar before,so has Taker (handicapped matches, and triple threat matches,) Jericho has never faced Lesnar so it doesn't hurt Lesnar. However, it will help Wyatt.