Riley is damn good and will continue to get better for a long while. Tony Hawk if anything will slow down. The new generation surpass the old, as it has happened in skating since it began, no big thing. You still can't compare them, one is a modern street skater the other a classic vert guy. They are night and day. One thing though, I seriously doubt that Riley no matter how good he gets will ever have the massive impact on skating that Tony had. Few if any will ever be that big again.
Oh and Tony's early 90's street stuff ruled.