1) Trump's threatened tariffs were a negotiating tool, to get the Canadian, Mexican and Chinese governments to drop their own disproportionate tariffs on U.S. goods imported to their countries. And primarily to get these countries to stop the flow of Fentanyl coming into the U.S. from these countries, and stop the massive flow of millions of illegal immigrants annually coming into the U.S. from these countries. There was never an intent by Trump to impose these tariffs, only to negotiate a better deal by threatening to.
And as quickly as these tariffs were proposed, all these countries (with the one exception of China, so far) have all conceded to Trump's demands and agreed to deploy troops to prevent illegal immigration and drug trafficking from their side of the border.
And China as well will have to inevitably concede, because they are far more dependent on U.S. markets than the U.S. is on Chinese imports.
2) Worst case scenario, if the tariffs were actually imposed, this would just incentivize publishers to shift all their printing and print supplies for making comics to domestic companies.
But as you already posted, the quick concession to Trump's demands has made that unnecessary.