To me, the prospect of isolation, of turning inward, scares me. It puts into mind Cuba, North Korea, to a lesser extent, Russia; the ratcheting protectionism and extreme nationalism during the Great Depression that lead up to World War II - and to this teenager, the United States has always stood for the opposite of that - deeply international, highly inclusive, and free; a global superpower open to investment, where the brightest minds and ideas come together.
Excessive isolationism closes off a nation from other ideas, creating an intellectual and social abyss. It fosters extremism and scapegoating, reinforcing fear and paranoia. Yes, some elements of international competition seem a bit daunting, but without it, I would imagine an isolated nation too boring and homogeneous to succeed, and my quality of life would turn for the worse.
I do agree the U.S. is no longer in a position to meddle with other countries' affairs - we no longer have the money, resources, energy, or standing needed to police the world. We have our own issues to deal with at home. Other nations have grown, and while the U.S. obviously remains a populous and important country, our sphere of influence will inevitably diminish.
But retreating to complete economic nationalism would be a disaster, IMO. Unemployment would shoot up, economic development would halt, and the world will become a far more hostile, war-prone place.
I don't believe the globalization model has failed - but rather government leaders have failed at being responsive to their constituents' concerns about globalization. The benefits of trade and free markets need to be distributed to more of the population, not just the elite. A stronger social safety net - one that includes education and retraining - would protect laid-off workers, without starving the economy of future opportunities.
Europe and Japan have long subsidized inefficient producers, at great loss to social welfare. With our more populist president, the United States is likely heading down the same path (to a much lesser extent), yet I think it's an inevitable and needed balance. I think of my impressions of Italy - not much economic growth, little incentive for mobility, a bit of restlessness, but a traditional way of life is maintained - with nice food, lots of small businesses and farms, a good standard of living, so long as you're an Italian national. It's a slightly depressing yet romantic view, as we hand the torch to the next superpower of the 21st century, content with our own past successes.