Was there ever any doubt that the Nintendo 3DS would sell an insane amount of units? If you had your doubts, what planet are you living on? This is the 3DS we’re talking about here, the successor to the DS, a handheld that’s sold over 140 million units worldwide as of December 2010. Nintendo hasn’t issued any official figures yet, but it’s already tooting its own horn, proclaiming, “U.S. day-one sales numbers for Nintendo 3DS were the highest of any Nintendo hand-held system in our history.” Official figures with first-week sales will be released on April 14. All in all, it seems like the 3Ds is off to a good start, now can it maintain the momentum? As we reported yesterday, the 3DS sold out almost instantly in Japan, but a month later, there are plenty of used units sitting on store shelves. Will the 3DS face the same fate? Is 3D just a gimmick? This is going to be very interesting to monitor over the course of the next few months.