And a US/Canada merger really doesn't make any sense. For starters merging two economies of that size will just be a disaster for both.
Canada's economy is already integrated into the US economy. 85% of Canadian exports, IIRC, go to America which is probably rather close to the percentage of exports that go from one US state to another place inside the country. Plus with NAFTA and continuing economic agreement and cooperation in a continually globalized market US and Canadian economies could coalesce very easily.
I think the Canadians are smart enough to get there heads around a Presidential system of government. They aren't dolts. Also they could continue having parliamentary state governments, just as Nebraska has a unicameral parliament or how Illinois used cumulative voting for its State Congressmen until the 80's. Most current laws within Canada dealing with taxes, public healthcare, and regulation are either set or administered by the provinces so these could easily be continued as differing regulations within the state. A Canadian province turned state could have higher taxes and public healthcare if they wanted to just as some states, like my own, have higher business taxes than others and just like states, such as Florida or Alaska, have no income tax at all since a state is allowed to set its own state tax rates.
