The Undertaker vs. Sting: Pipe Dream or Possibility?

A couple weeks after the Royal Rumble and before the Elimination Chamber and less than 60 days before Wrestlemania 27, speculation and rumors fly as they do every year.  Last week's episode of Raw featured a vignette of a small house in the rain and a mysterious figure walking into it.  Only shown is the person's black boots and bottom of a black trench coat, after that the date 2/21/11 was flashed on the screen.  For over a decade, the marriage of pro wrestling and the Internet has created more false reports than actual ones.  A jumped conclusion was that the mysterious person was Sting, who wears the aforementioned black boots and coat.  The logical conclusion would be the character that's been with the WWE for over 20 years who also wears black boot and coat, The Undertaker.
Between the 2/21/11 promo and the unexpected returns of Diesel and Booker T, the rumors of Sting jumping ship from TNA to WWE began.  And appropriately during the road to Wrestlemania, where the personification of WCW can wrestle on a stage he's never been on, Vince McMahon's ring.  Who better for the Stinger to face off against than The Undertaker?  Message boards, Twitter, dirt sheets all reported and talked about the possibility of a dream match that everyone would love to see.  Fans created very cool fantasy posters, such as the one that is featured above.  And because Sting is currently a free agent, the excitement and rumors even larger.  No doubt that the brass at WWE and even Vince McMahon are aware of the demand from the fans.  Last night's Raw, had another 2/21/11 teaser, but this time around the promo ended with Johnny Cash's "Ain't No Grave" heavily implied that it is indeed The Undertaker.
Vince knows that this dream match would create a good revenue for Wrestlemania, and it's the big draw the card can use.  But is this a match is most likely a fan demand.  Ideas for Wrestlemania and story lines are written months in advance, sure it's subject to change, but was this really in the grand scheme heading into 2011?  Would Sting even want to work the match?  And what kind of effort, if any, has McMahon put into making it happen?  Is this a fan dream match spun out of control by the power of the Internet?  Or will we really see the only remaining big star in my lifetime to never wrestle for the E to actually be at Wrestlemania?  If you were to ask me, I'm going to say no, but I'm not going to rule it out either.