I would suspect a lot of people will drive for a vacation this year to Chicago or perhaps to Cleveland. In the event I vacation again in MI this year I suspect Canada is out of the picture this year if for no other reason than been here done that. Besides I do think its about time Canadians stopped taking our patronage for granted.
I'm sure outside of those with family in Canada or work there, the tourism will certainly decline, if for nothing else, the border checks and the wait.
If you like scenery, you can't beat North MI, especially the Mackinac area. There's a reason Michiganders always talk about "up North". Just watch out for the deer.
Traverse City/Leelanau/Boyne/Petoskey is also a great area along Lake Michigan.