I'd say we're already there, and have never really left it. In my opinion. the noble/serf arrangement has always been in place in America.
I did a bike ride across the country about 10 years ago, and it was eye opening. Much different than what I saw everyday in Orange County, CA. It's easy to keep the blinders on in our everyday lives.
No slums like bombay or Sao Palo or mexico city. Thankfully, our poor (even our rural poor) are spared the intense and catastrophic destitution of such places. America is not a classless society, but we have maintained a large and healthy middl class (that is less true now than it once was,) and as previously mentioned, our poor are better off than their counterparts around the world.
I did a bike ride across the country about 10 years ago, and it was eye opening. Much different than what I saw everyday in Orange County, CA. It's easy to keep the blinders on in our everyday lives.