Absolutely this will be a problem with US production in Canada. Mr. Trump's goal is to get any manufacturing and most business to locate back south of the border. Can't see why film and TV production would be any different. And Trump is very interested in media.
In addition to our crews and studios our big advantage, as already mentioned above, would be the difference in our dollar. To a lesser extent tax incentives. However most American states also have tax breaks and incentives for film/TV production, so these aren't as big a deal as before.
Like everything else, it will come down to money. Even with tariffs or anything else the US government has in mind, if filming is still cheaper here, production will mostly continue. If not, or no significant savings, it is good-bye.