Yeah I do not see anyone on the horizon in the US who could be MotoGP champion. Spies might have had a shot if were not for injuries. If you look at the MotoAmerica field by the time you get 8-10 riders down the field they are 2 seconds a lap off the pace, and a MotoGP reject (Elias) is often at the front. Nicky had a combination of talents that are unusual in this generation in that he also won pro dirt track races (I think he was only missing a mile win to have the elusive grand slam). When he went to MotoGP in the early days of four-strokes in 2003 he showed improvement every year: his qualifying got a bit better, his race times and tire management improved, his race craft...basically 2003-2005 put him in the right place at the right time (on the right bike with the right set of skills) and he won that one and only championship. Unlike many that flame out or burn out, he was able to keep a ride in MotoGP for almost a decade after that. When Rossi and him were teammates again at Ducati neither set the world on fire because the bike was bad, but Hayden's finishes were comparable to the GOAT's. Sad day.
Truly charismatic. I recall he had a reality show a while back, one of very few I've ever enjoyed watching. This is crushing news to me. Seems so unfair for such a person to die so young....