According to PWInsider.com, original WWE SummerSlam plans called for The Hardys vs The Revival to take place on the Kickoff pre-show. However, with Scott Dawson suffering an injury, the match has been scrapped altogether. The belief is that The Hardys will face the team of Luke Gallows and Karl Anderson on the pre-show instead.
There are also plans to run a tag team match on the pre-show, and that could be The Usos vs The New Day for the Smackdown Tag Team Titles, however that has yet to be confirmed.
There should at least be two matches featured on the Kickoff pre-show, as it begins at 5pm EST and is two hours long. As noted, the show will be hosted by Renee Young, Peter Rosenberg, David Otunga, WWE Hall of Famer Lita and WWE Hall of Famer Jerry Lawler.