I know I said this match has almost no chance of happening, but for this article I'm using the "perfect world" stand point.
So here's how I see it going down.
The Royal Rumble is in full swing, we've seen 29 wrestlers announced, just as the countdown strikes "0" the truck horn blares and Big Daddy Cool Diesel comes strolling out.
A couple of big boots and some close lines and the ring is empty except for one man, Diesel.
The next night on RAW he announces he doesn't care about the WWE title, it's worthless to him, all he cares about is ending the WWE career of the man who essentially ended his, The Undertaker.
For the next couple of months we go through some severe mind-games, much like we saw leading up to Wrestlemania XII, coffins, hell-fire, sneak attacks, you know the works.
After all of this The Undertaker sets the stipulation as a "Buried Alive Match".
Finally we come to Wrestlemania, even though there is no title on the line this is the main-event in everyones' eyes.
For the most part the match is back and forth, but Big Daddy Cool holds the upper hand for awhile. But the Undertaker fights back.
He walks the top rope and crashes down on Diesel's arm. The Taker then slowly draws his thumb across his throat and the crowd goes wild.
Just then the lights go out. When they come back on Shawn Michaels in his white hat and trench coat is standing behind the Undertaker.
He delivers Sweet Chin Music causing the Undertaker to stumble right into Nash who delivers a devastating Jack-Knife powerbomb.
Both Nash and Michaels bury the Taker and that is the last the WWE sees of him.
After Diesel delivers the powerbomb Taker kicks out. He then sits straight up. Both Michaels and Diesel try to beat him down but can't.
Taker delivers a double choke-slam to them and then tombstones Nash. After the 1-2-3 The Undertaker burries them both and leaves Wrestlemania and the WWE 19-0.