#3 Roman Reigns already has an ongoing feud for SummerSlam
This week on Raw, Roman Reigns and Samoa Joe took part in a 'Samoan Summit'. Obviously, it ended up being a big brawl. Drew McIntyre and Cedric Alexander joined the fray, signaling that the Scotsman's beef with Reigns is not yet over. WWE could club the two feuds and have a single tag team match at SummerSlam, despite the scaffolding attack on SmackDown.
The Big Dog could instantly blame Joe for the attack, with the former NXT Champion neither accepting or denying his involvement in the attack. The rivalry would at SummerSlam before the mystery attacker shows himself after the pay-per-view. It has been done before, between Nikki Bella, Carmella, and Natalya. WWE should just not leave this stone unturned, especially after the show-closing brawl on Raw.
If Roman Reigns does face his attacker at SummerSlam, and it is not Samoa Joe, that leaves him in limbo for next Sunday.