Theres a couple of things wrong with this idea. First of all having Orton beat Taker at Mania would definately turn him heel. WWE wants him face and they're having enough trouble keeping him that way since the whole Christian debacle. Second, Orton wouldnt gain much from beating Taker at Mania. Hes as much of a household name now as hes ever going to be. If he hasnt "made it" with his most recent title reign then he probably never will. Third, Taker deserves to retire with the streak in tact. Really, he has 1 or 2 more Manias to go. Hes obviously going to get a rematch with Triple H and then he might give some rookie or midcarder a match just so he can get a descent push. This year would be great for a Taker vs Wade since Wade's an incredible talent whos being horribly misused. But to answer your question, we already had Orton vs Taker, and it was great back then, but it wouldnt work now.