My guess is that protectionism will bring certain sorts of jobs to the USA. Rust belt types of job. It will also make the goods those jobs generate more costly.
At the same time, retaliatory tariffs will ensure that US exporters will have a hard time, which will lead to lost jobs there; and the loss of exports and imports will make the global economy less efficient, including the US.
So I expect the global economy to do poorly and China to dominate international trade.
In this Trump/protectionist world, America will likely do better than Mexico, say. And this will lead to the renewal of mass immigration. The wall won't prevent it. People will enter the US on vacation visas and stay on.
All good, clean fun. Trump will blame foreigners for all of this, and his supporters will also try to shirk their responsibility. As is already happening.