Based on this year's qualifying criteria, all of the following are guaranteed one event, if they decide to skate seniors, and pairs can skate both juniors and seniors (and pairs don't skate in all JGP events):
Zhang, Nagasu, Czisny, Wagner, Oster, Liang
Carriere, Mroz, Abbott, Bradley
Vise/Trent, Namiotka/Coughlin, Vlassov/Meekins, McLaughin/Brubaker
Hubbells, Samuelson/Bates, Navarro/Bommentre
Meissner, Hughes, Lysacek, Weir, Belbin/Agosto, Davis/White, Gregory/Petukhov, Inoue/Baldwin, Nam/Leftheris (based on score) and Castille/Okolski are guaranteed two.
If the USFS wants to give exposure to the greatest number of skaters, they might choose someone who isn't guaranteed any event or doesn't qualify for one, knowing that the rest will get at least one.
Of course, from a TV standpoint, Vise/Trent attempting a quad throw vs. Inoue/Baldwin's throw 3A, Zhang's flexibility, Bradley the crowd pleaser, a Weir/Lysacek preview of US Nationals are all good stories, and you never know whether this will have influence in the final selection.