50 million would be okay, it will sell more though. I remember how 90% of the site said I was being ridiculous a couple of years back when I said that the 3DS would sell a lot less than the DS and possibly only half, lifetime. And here we are.

50mil units x $200per unit= a whole lot of $$$$$$$$$$. Now when you add the $$$$$$$$$$$$$ made from the games sold its a crazy success. So, $$$$$$$$$$(units sold) + $$$$$$$$$$$$$(games sold)=$$$$$$$$$$$$$$$$$$$$$$$. They may have wanted to make more $$$$$$, but things didn't go so smooth at launch.

my math maybe a off just a little.

http://en.wikipedia.org/wiki/Opportunity_cost

I'd call it a failure if it sold 50 million life time. Nintendo would have lost 2/3 of the audience they generated with DS. It's not a success for Nintendo if they sell 50 million units of a console because of changes in the market, it's a mark of their failure that they didn't take into account those changes in the first place.