How about Shawn Michaels vs Triple H vs Undertaker? That could be an excellent match and it would be different than last year's.
Simply put, no.
Here are the reasons.
1. Undertaker has beaten both Triple H and Shawn at Wrestlemania. Now while Shawn is ok with going down for Taker, Triple H will not do the same. It was noted a year ago that Triple H wanted to end Taker's streak as "revenge" for the win at Wrestlemania X-Seven.
2. Hunter and Shawn in the ring are a bad idea because they simply want to be in the spotlight for more than 20 minutes. Even when neither were in the title picture during 2004, they were Main Eventing with matches like the 40 minute Cell match! Also, most likely, the creative clash given the three men's respective status in the WWE.
3. Triple H will want to be in the title match at Wrestlemania, simply put. When was the last Wrestlemania he was not in the title match outside of injury? Wrestlemania 17 to be exact, he's always been in a title match since.
Please keep in mind this is about why Taker/HBK 2 is a bad idea, while it's good to suggest ways of making it interesting, but it's focusing purely on the rematch itself, adding Triple H to the mix makes it not a rematch but a different match all together.