The following should be considered as unconfirmed rumors at this point
— The backstage plan is for Finn Balor to re-introduce the “Demon” character sometime during his current program with Bray Wyatt. WWE has already begun hinting at this as recently as their Raw preview for tonight’s show, but it’s more likely to happen at SummerSlam.
— Chris Jericho is not officially back with WWE fulltime and is also not expected on Tuesday’s Smackdown. Jericho will be missing more time again in the October-November timeframe, but there’s a good chance he will be a part of SummerSlam in some capacity.
— According to Sportskeeda, Kurt Angle will be involved in a storyline with The Miz over the next few weeks, much like the Miz/Daniel Bryan program that took place on Smackdown earlier this year. Miz is expected to defend his IC title against Jason Jordan at SummerSlam.