Want to know what the US will be like? Just look at an island.
Nobody makes things on islands, it's too expensive compared to the mainland.
The rich vacation there and have large expensive homes. Real estate is big, so is tourism. Some service industries exist, simply because you can't get take your house to the mainland to be painted, for example.
There's lots of entertainment for those with money. Nightclubs, yacht clubs, restarants, movie production, etc..
There's usually a very small middle class on islands. They work in the service industries that cater to the rich. They live in very meager accomidations because of high real estate prices in decent areas, and are often seasonal guest workers from the mainland who live in dorms and save money to bring home.
Most of the upper class on an island makes their money on the mainland. A few of them own local businesses. They live in heavily guarded communities.
The lower classes of islands are some of the poorest and most destitute people on Earth. They lack every basic necessity and scratch out a marginal subsistance life in slums. Lower class areas are rife with crime and violence, and many of them prey on the rich, who carry more in their wallets than some of them will make in 20 years.
So that's it. The US is the island and the 3rd World is the mainland. Sounds like fun!
The sad thing is, there are some who would celebrate the scenario you just penned, if it indeed came to pass, as the triumph of free trade (which really isn't) and the wonders of unfettered capitalism at its finest. You got rich people? Great! Good for them! They deserve it. They worked hard destroying companies and pocketing the savings and cancelling pension plans to put the cost savings on the bottom lines and earn $50 million bonuses for doing so. You got middle class in service work? Right on! The "free market" determines where they "fit in" best! So what if they spent their lives educating themselves and trying to build a better life for their children. Let them be cooks and housecleaners for the upper classes if that's where the marketplace tells them to go. You got millions of poor people living in squalor in slums, with no hope of lifting themselves out? Well, heck, screw 'em, it's their own fault for choosing the wrong career, like IT when everyone could see how the CEOs were sending that work to India. But, never, ever advocate anything like tariffs or measures to encourage preservation of basic industries or infrastructure, because that isn't classically "conservative". "Free trade" at all costs (even if it destroys you).
(/sarcasm)