Cody Rhodes is slowly becoming more dangerous and aggressive inside the ring. Two weeks ago on SmackDown, he attacked Cena using the title belt, a tactic he had previously avoided.
At a recent Fanatics Fest, Cody even hinted that the end of his babyface run was near. WWE Creative could accelerate that process, making him the villain at SummerSlam by beating Cena through underhanded means.
This turn would work perfectly if Cena is meant to go face again before retirement.