There has never been a time where America wasn't segregated or in equal. I think throughout America's history we've had a long runway: the fact that the continent was open to use w/o a well organized Mexican or Indian state to stop expansion, the isolation from WW1 & WW2, the fast amount of land in this country and natural resources, the decline of Europe and relative weakness of China, etc. We've been able to take advantage of these conditions for 200+ years. The rest of the world is catching up though, we will need to really unlock the potential of people who in the past have been marginalized to continue our run as a superpower.
The wealth gap isn't even as bad as it has been before. During the industrial revolution Rockefeller amassed so much wealth he puts modern billionaires to shame. Unlike 100 years ago, however, we've severely raised the economic floor for our population.