Taker showing was unexpected, but like I said, I'm a Taker-stan, so I'll take it over Stone Cold showing up.
All in all, though, great Mania, and as close to a perfect ending for a story, that you can get.(Hope they have a new one already cooked up for Cody, so he can keep the steam going.)
TL;DR:
Dusty was The Undertakers first opponent, he bailed out The Rock when he fought against McMahon and Helmsley(Thus would hate what The Rock has become) and Roman and Taker was Mania opponents and Heyman was his manager and took him to the WWE in the first place.
i.e. The Undertaker is PERFECT to have been there rather than Stone Cold.
The next PPV might end up being the most appropriate title, too. Backlash. We gonna see how well they do, and how much of a flaming it might need, in certain parts. Looking forward to it, Darth, assuming I can make it.