WWE is currently planning to have John Cena face CM Punk for the WWE Championship at SummerSlam on August 19. The plan is to build the show around Punk/Cena and Brock Lesnar/Triple H.
WWE decided to go with Cena and Punk for the second year in a row because they do not want their biggest draw to be in the fourth most important match, meaning Lesnar/HHH, two world title matches and then the Cena match.
Since Summerslam is one of the biggest PPVs of the year in the major television market of Los Angeles, California, WWE wants Cena in a title match and on top of the card.
As always, plans can change. We'll keep you posted.