I would not be against such additions to the country.
The main problem as I see it is that each new province has too many people in it, especially I think New America. So that would really shift representation in a completely new direction. The political views of the new Canadians wouldn't be so radically different than that of Canadian norms, so that shouldn't be a problem at least, but basically these Americans would have to be Canadianized in stages. So that by the time Baja Canada joins the country, New America is already addicted to Tim Horton's and playing hockey in the streets wherever possible.
Quebec might have a big problem with the addition of so many anglophones to the country, and people from California might have a problem with having to learn French.
I also like that special care has been made to exclude Gary, Indiana from Canada. As per our constitution this must never be allowed to happen.