Riley is new to the catsailing scene, he is only 19 after all, but has a fair bit of international experience according to google. It appears to that him and Louisa gelled in Miami, but it was a relatively small fleet, without the foils, and more concerning is the british squad were pretty dominant. Without someone else to push them hard, I'm not sure our chances in Tokyo are any better.
Easton isn't just a local stud, him and Burd have won races at the highest level of the sport and finished 10th out of 118 back in 2012 at the F18 Worlds. He doesn't need my defense, I can't say if he'll be back but right now the U.S's problem is finding and developing talented crew for sailors like Easton, Riley, Bora, and developing the next generation looking beyond 2020. I do know that Bora will be back, he has a small fleet of Nacra 17 Mk. 2's on order.