It's going to end up nowhere close to DS sales over here. The DS used to crush 400k-600k even in a month like February, 3DS is putting up 190k in Feb with two hardware models, three big Mario games, Kindgom Hearts, Resident Evil, Kid Icarus, etc. all available and a new Fire Emblem bundle for the month too.
It's only in Japan where it's really selling great.
But its got Pokemon coming up at the end of the year. 3DS may not reach DS levels in America, but it's still a healthy platform to release games.(at least for Nintendo)