At this time, it appears as if a Brock Lesnar vs. Triple H rematch will take place at WrestleMania 29. Lesnar is expected to return to WWE TV sometime in February and will then make regular appearances to build to the WrestleMania 29 match.
Lesnar's current deal will end right after WrestleMania. The feeling is that WWE will offer him another deal, as they were happy with the pay-per-view numbers as well as Lesnar's performances against John Cena at Extreme Rules and Triple H at SummerSlam.
If Lesnar doesn't sign a new contract, WWE will be faced with a the annual "WrestleMania hangover" dilemma of their special attraction talents (Lesnar, The Rock, The Undertaker, Triple H) all leaving once again. None of these guys will be working a full-time schedule following WrestleMania 29.