This could be an interesting experiment/learning experience..
I mean, my instinctive thought is that those tariffs are going to be a disaster - driving both inflation and unemployment. Objectively I should be hoping they don't happen, because the chances are they will be bad for everybody.
But it could be instructive to learn just how far one can go down that road before the costs exceed any benefits. In some ways there might be some upsides to such a regime - allowing the growth of domestic industries that need a lot of capital investment, and reducing the complexity of the tax system. Maybe. It probably depends on the level of development a nation is at, and the state of the global system. It will just be interesting to see what happens.
Sounds as if Trump is proposing 'testing to destruction' though (because he's nuts), so probably won't be fun for us test subjects. It seems consistent with his entire agenda, of rolling everything backwards, and trying to use brute-force to force things to return to the early, pre-WW1, pre-WW2, pre-Great-Depression, days of capitalism.
Seems to me there's an interesting question there, as to whether such hankering for a golden age is in any way sensible. Most leftists I know see the changing nature of the capitalist system as being part of an inevitable, inexorable process of decline, the working-out of its inherent contradictions, that will end in either socialism or barbarism. Whereas Trump seems to represent a strand of the reactionary right who think the system can be rolled back to that golden age, by sheer force of will - a belief that seems to conflict with technocratic capitalists just as much as it does with Marxists.
It's intriguing that the US first rose to dominance under a highly-protectionist regime. It only embraced 'free trade' once it was in a position to benefit from it. But can one simply _force_ the system to return to its earlier condition, even while everything else in the world has changed? Will it also require a rolling back of everything else to pre-early-20th-century conditions (e.g. bringing back slavery, a return to 19th century living standards, a return to old-style imperialism, etc)?
I'll be a little disappointed if Trump simply fudges the whole thing and doesn't actually put his ideas to the test, even if, in reality, that's probably the best outcome one can hope for.