Demos are marketing, as well as the limited edition. The game is out in October, so let's wait to see how they will push it in stores and TV.
You can wait, I can comment on what I feel is realistic. There is hardly any real marketing at all for the title, and it is being positioned as a niche game targeted at a smaller core fanbase. This is why they are marketing it the way they are, through Facebook, a few magazine articles, and demos on the eShop. This sort of marketing format is cheap and mostly the responsibility of the development staff, which shows the company doesn't view it as a significant investment at all. This also generally translate into low shipments, and along with the fact that most average consumers won't know or care what the game is, it won't sell a lot. Keep expectations low.