If you wanna support the game, buy the game sooner or later. The only way to get it at a lower price is buying it used or being lucky in getting a discount. Nintendo games rarely get a price drop (whether its controlled by Nintendo or not). Xenoblade Chronicles got up in price over the years until it got a European VC release so I doubt X will be any different unless it reaches at least close to a million to be considered as part of the Nintendo Selects.
As for reaching 1 million, I'd say wait and see since its still early. Do you know how long it took Donkey Kong Country Tropical Freeze to get to a million or even Pikmin 3? Yeah..