As of now, WWE is discussing two major main events for this year's SummerSlam PPV, reports The Wrestling Observer.
We reported yesterday that current plans call for Cesaro to be a top baby face in the company in the coming months, and should WWE maintain that trajectory, then a likely Cesaro vs Brock Lesnar match would take place at SummerSlam this year. The plan would be for Cesaro to eventually split from Paul Heyman, setting up the match between the former "Paul Heyman guy" and Brock Lesnar.
Prior to WrestleMania 30, plans were for Roman Reigns to be pushed as a major singles baby face in WWE in the coming months, and with yesterday's report that The Shield is expected to stay together as a top face team in WWE, that could be where WWE is heading with Reigns. If WWE does continue in that direction, then a planned Roman Reigns vs Triple H match at SummerSlam could take place, as has been rumored for quite sometime.
If both the above matches take place at the big event this year, Cesaro and Reigns would likely go over in their respective bouts, to help solidify them both as main event players in WWE.