I don't know if I'm alone in this, but I think my interest got killed in seeing Cena wrestle again.
Everything about SummerSlam felt like his last match. The fact that he went up against the current top guy, the fact that it was for the title, the fact that he turned face for it, the fact that it was a finisher spam fest that went almost 40 minutes, the fact that he passed the torch to Cody. Cole even compared it to when Cena beat Rock and Rock passed the torch to him. None of his matches moving forward are going to have the same meaning because there's nothing to be invested in.
He'll probably lose his next couple matches, get killed in his hometown by whoever, and get the big send-off as planned. But when I really think about it, Cena's career ended on Sunday and I'm okay with that.