Let's face it, most people bought more than one DS (some people bought 3 or 4) The difference between the fat DS and the DS light was huge. Many people that bought the DS fat bought a second DS eventually. The 3DS does not have a notable upgrade. Everyone who buys a 3DS keeps it and is satisfied with it. the 2DS is for people who just want to play a few games for as cheap as possible. I'd say actual unique playes that own the DS is somewhere around 100 million not 150 million.
The DS fat also had a hinge problems. Many of the older design had split into two. MANY people bought a second DS because of this hardware failure. We should look at popular software sales to determine how many unique players there are. Pokemon is the best example because every pokemon fan that owns a handheld WILL buy a pokemon main series game. What we do know is Pokemon X and Y is heavily outselling diamond and peal if you align the launches.
-The Vita is failing so hard that it gives Nintendo pretty much a monopoly in the dedicated handheld market
-The 3DS is single handedly crushing every console even the PS4 just like the DS crushed every console on the market
-Nintendo realizes that the Wii U may never profit so they are going all out trying to make handheld sales the best they can be
-The only reason the 3DS appears to sell slower than the DS is because of the horrible start it had
-Software sales on 3DS appear a lot smaller than the DS because a lot of games, especially in Japan, sell very well digitally
