I was thinking about Survivor Series before, and I really think that the WWE can do somehting with that. A modified War Games Match between RAW and SmackDown! would really get things going well.
Why not do something really interesting here, and have John Cena LOSE at WrestleMania, due to Batista costing him the match. Dave explains that tonight was his night, he does what he wants and he doesn't want Cena to take away from that.
This can create a rivalry in the brands, with Jim Ross & Jerry Lawler saying that WrestleMania was Batista's night being that he won the Royal Rumble. On SmackDown! they say that SmackDown! was going to crown a new WWE Champion until Batista interfered.
I haven't watched the finish again yet, but in the Royal Rumble this year, I think I remember John Cena's left foot landing on Batista's back when they did the double-elimination spot. If this did happen (I'm really not sure), they could have Cena play that and say that technically he deserved to win the Royal Rumble.
A match between the two at Summerslam would really make the show worth watching, in my opinion. Maybe even keep Cena AWAY from the WWE Campionship until then?
A while ago I made a post about how I would like to see the King of the Ring tournament go, if it was reinstated. Cena can qualify for the tournament because he hasn't been a World Champion before. In the finals we have Edge vs. John Cena, with John Cena picking up the win and getting is choice of World Champion at Summerslam. He chooses Batista and away we go.