Also more incentive for people to actually manufacture stuff locally, so there is more variety other than just chinese slop, and an opportunity to show that NA products are superior. Also having sovereign manufacturing bases for tech (although this seems less likely and trump already exempted those)

If its simply too expensive to import than there is an economic opportunity to take a stab at doing it locally. If there is no incentive because you can never beat the cheap labour in China then noone will even bother to try.