Simone is really something, the likes of her we will probably not see again in our lifetime. She'll probably want to go out with a bang in Tokyo, and is already on the right trajectory.
Will USA fall back without Simone? Probably, but Simone has inspired lots of girls to try gymnastics for she is so likeable. And she has shown what work is needed and how to persevere, survive and regroup.
Will the playing field in the team event be more equal? Russia the perennial silver medalists, China the bronze? Will they shuffle their places on the pedestal around? Neither seem to be able to break to the top like Romania has done so many times, the Russian team is getting old and crippled, the Chinese too young and unstable, BRA, FRA, ITA, ...
Russia with its huge resources always have these outstanding juniors, but the Rods run them into the ground or injury before realising their full potential.
well let's look at who else the US has, not considering if anyone retires after the Olympics-
Riley McCusker- a strong all arounder, great on bars, wonderful grace and dance, Nastia-esque
Suni Lee- another strong all arounder, even better on bars, seems relatively steady
Grace McCallum- reliable, another relatively good all arounder, but nothing really "star" quality about her gymnastics. She delivers when needed, but not a top scorer.
Kara Eaker- good beam specialist but a bit nervy, can be used on other events if needed.
Jade Carey- very strong all arounder, even stronger on vault and floor, has some really hard skills in the making, like a triple-double on floor. She could also be a team leader.
McKayla Skinner- a bit rough around the edges and needs some polishing/cleaning up with her form, but can be counted on for most all events except for bars. also can do some tough skills.
Morgan Hurd- had a rough season this year and didn't make the world team, but is a good all arounder when she's on. 2017 world aa champ, very musical and nice to watch. hoping she comes back strong.
Jordan Chiles- US silver medalist in 2017 (i think) but has struggled since. good on vt/fx.
i think that's most of the big names, not sure who else is coming up in the junior ranks as a new senior next year? last i heard Laurie Hernandez is still working on a comeback for next year.