Triple H's mention of The Undertaker last night was starting the build to a rematch between the two at WrestleMania 28 accroding to The Wrestling Observer.
It's also been reported that CM Punk vs Chris Jericho is penciled in and obviously The Rock and John Cena will take place in Miami at WrestleMania. Those two match plus The Undertaker vs Triple H is said to be the triple main event that WWE is looking to bill WrestleMania 28 around.