Yes, the area does provide some interesting geography, mirroring Europe to some extent, though on a somewhat different scale. Depending on where you cut things off, eastern Asia certainly has potential. Southeast Asia and Indonesia provide some similar areas, as do, the Caribean and Gulf of Mexico, and the landmasses around the North Pole. Variant designers creating maps featuring other areas have to find ways to compensate, or work around the geographical disadvantages.

But what is also usually necessary is appropriate history to go along with the geography. A lot of people are not interested in fantasy/science fiction type variants. They want to play in a scenario that bears a fair resemblance to actual history. This usually means having multiple Powers, on a relatively equal footing, with additional smaller nations around that will become neutral dots for the Powers to expand into. The problem with eastern Canada and the United States lies in the lack of such history. One or two Powers have always been dominant, and small neutral states haven't existed.

I don't want to discourage you, but rather just point out some things you might want to bear in mind. Good luck with your project.