Nintendo of America president Reggie Fils-Aime kicked that assumption in an interview with IndustryGamers. "The one thing, for sure," Fils-Aime said about the 3DS release plan, "is that we will launch in all of our major markets by March 31, 2011." As for the specific release dates, Nintendo is still "making individual market decisions in terms of what's happening in Japan, what's happening in the Americas [and] what's happening in Europe." It's worth noting that the last two DS systems launched in the spring in North America: DSi on April 5 (2009) and DSi XL on March 28 (2010).
Fils-Aime also reiterated that the design of the device seen at E3 is not final, so don't get married to the analog stick placement or those shiny paint jobs just yet.