The Dreamcast's Japanese launch was a complete disaster. It literally only had four games, and they were all terrible. Shockingly they didn't sell many systems at first...
Its US launch (which was almost a whole year later) was considerably more successful. Probably Sega's most successful launch, though it still doesn't even come close to what the PS2 did the following year. It's all relative, I guess.
Anyway, this is Nintendo we're talking about. They certainly have the production capacity and we're still a couple months out and yet Gamestop is no longer taking pre-orders since they're all sold out already. What does that tell you?