Goldberg isn't likely to be around WWE for much longer than WrestleMania, so WMXX will likely be his last WWE match. And, the cynic in me says that any World title match for WrestleMania pretty much has to involve Triple H in some way (probably with him going over yet again).
Also, I truly think that Undertaker will never lose at any WrestleMania to anyone. If he didn't lose to Triple H or Flair, he sure won't be booked to have the streak broken by Kane.
"When this bogus term alternative rock was being thrown at every '70s retro rehash folk group, we were challenging people to new sonic ideas. If some little snotty anarchist with an Apple Mac and an attitude thinks he invented dance music and the big rock group is coming into his territory, [that's] ridiculous." - Bono, 1997
Goldberg did standing backflips. As I recall, his alleged martial arts skills were a promo by Bischoff to give him the aura of a shoot fighter in the mold of Ken Shamrock. But I'd still think it would be hell of a street fight.