North American Currency Union?
He does however say that this presupposes free movement of labor. Actually, monetary unions don't presuppose this in order to work as long as prices are reasonably flexible. The real argument against this plan from a Canadian perspective would be if it would really be wise to allow their monetary policy to be run from a central bank with such a inflationary track record as the Federal Reserve.
And in reality, nationalist or anti-globalist sentiment in both Canada and the U.S. is likely to prevent this from happening anytime soon.