#1 Constable Corbin

Given the freshness of the storyline and WWE's love of overbooking things to include an authority figure's influence, Constable Baron Corbin will assuredly make an appearance and get involved in the festivities.
How and to what extent he'll exert his power is a complete unknown, but it's very unlikely this event will go down without him doing something to badger Kurt Angle.
He shouldn't have any jurisdiction over the SmackDown-only matches, so the tag team, women's and WWE title matches, as well as Daniel Bryan vs. Big Cass, should be immune to him, but everything else is fair game.
Constable Corbin could get in the way of Roman Reigns and Jinder Mahal, Seth Rollins and Elias, reverse the referee's decision of a Ronda Rousey title change or mess with the two ladder matches.
Somehow, in some fashion, Corbin will screw over a babyface and revel in his antics while the crowd gets upset.