Although there has been some talk of having Dwayne "The Rock" Johnson face Brock Lesnar next year at WrestleMania 32, as of right now it seems more likely that The Rock will face Triple H.
The idea would be that Triple H would have his wife Stephanie in his corner and The Rock would have UFC fighter Ronda Rousey in his corner. WWE would very much like for Ronda Rousey to face Stephanie in a one-on-one match but the odds of that happening are very slim due to Ronda's contract with UFC.
Plans could certainly change over the next year, but for right now, The Rock vs. Triple H is penciled in for WrestleMania 32.