I think it's doable first year. It's going to be a big hit in Japan right out of the gate. The question is how it does in the long run in Japan. To sustain 5 years of great sales it's going to need Pokemon, Monster Hunter, and several hardware revisions down the line.
While I doubt it will sell as well outside of Japan as inside Japan, I expect global sales to be more stable overall than Japan sales, with lower highs but higher lows.