Complex sentence: The effects of America opting out of NAFTA would hurt Canadians more than most think, with the interconnected economies of America and Canada, and all the progress that has been made to connect the two countries even more.
Split into simpler sentences: The effects of America opting out of NAFTA would hurt Canadians more than most think. With the interconnected economies of America and Canada, and all the progress that has been made to connect the two countries even more.