Thank you for your question.
A lower tax rate in the United States will simply make large mergers easier, similar to when Burger King merged with Tim Hortons in Canada. That was partly thanks to our slightly lower corporate tax rate. If the United States was to drop its rate, transactions like these wouldn't be possible, and doing business with Canada would hold no appeal. Mergers of this type would no longer happen.
The NAFTA negotiations reinforce the need to make the corporate tax rate a higher priority. If businesses set up shop in the U.S. after the proposed tax reforms are passed, they will have even less reason to do business with Canada and find it harder to come back.