Looking forward to a great debate Adalam.
With that being said let's get onto the debate:
Why Undertaker's Retirement Party Does NOT Need to Happen at WrestleMania.
For nearly 20 years, The Undertaker has had a very lengthy and successful career in the WWE. 7 time Tag Team Champion, a Royal Rumble winner, a 7 time World Champion, and holds an 18 match winning streak at WrestleMania, quite possibly his claim to fame. When Taker finally decides to call it quits and hang up the boots, WrestleMania does not need to be his final resting place.
Tradition
As most wrestling fans know, when wrestlers retire, they symbolically pass the torch to the next guy by losing their final match (sans guest appearances). Pretty much all of the greatest have done it such as Stone Cold Steve Austin (loss to The Rock @ WMXIX), The Rock (loss to Goldberg @ Backlash), Hulk Hogan (who was scheduled to lose his final match in the WWE to Shawn Michaels but egos got in the way), and most recently Shawn Michales (loss to the Undertaker at last year's WrestleMania). Now as mentioned earlier, the Undertaker has had a fantastic career but, for him to retire and pass the torch at WrestleMania, the WWE would be taking away his greatest claim to fame. Taker's undefeated streak at WrestleMania is one that will never be duplicated any time soon and for him to lose that could possibly hurt his career as storied as it is.
Other Places for Taker to Retire
As the title suggests, there's a few other places where the Undertaker can retire. The one that comes to my mind with the current storyline between him and Kane is have him retire at Suvivor Series, the same pay per view he his first appearance. You could also start a program with Superstar A wanting to take out the Undertaker before he gets to WrestleMania and have him actually succed either at TLC, the Royal Rumble, or Elimination Chamber. Where ever the location, Undertaker doesn't
need to go out at WrestleMania.