It's unclear if it will have lasting power, but when do you guys really think Nintendo will drop this? It's a launch title, so it will eventually be 20 or 30 dollars, but Nintendo has a history of knowing when they have a marketable product. See: Mario Party 4, 5, 6, 7 - They're all 50 bucks. See: Legend of Zelda: The Wind Waker - It was 50 bucks for about 2 years after its release.
I think if Excite Truck really is a tremendously fun game, one of two things will happen:
1: It'll become, at least to an extent, what Mario Kart 64 was for the N64 - A game people will periodically be coming back to long into the next system's lifespan. This is unlikely, as Mario Kart 64 was a benchmark for Fun.
2: It'll be great for a time, and right before the expected price drop, players will trade it in while the new system trade-in deals are still in effect. This'll make it approximately half of a game. Nothing wrong with that.
Just what I've been thinking.