It honestly will depend on if Nintendo markets it right.
Since its release, the Xenoblade brand has become very respected worldwide due to many great reviews, the struggle to get it released in NA and its rarity. Shulk appearing Smash Bros was a good move, now Nintendo just has to promote it well enough to grab those that don't follow the game industry to want to give the game a shot.
Also it will definitely have to play just as good as the original or people who even haven't played the Wii game will hold its performance as a negative and not buy it. Honestly, unless there is a massive Xenoblade fanbase that has grown in Japan, I personally think it do on par with the original lifetime, it is on the New3DS only, I think even around the time Xenoblade 3D drops there still won't be that big of an install base outside of Japan.













