Last year was gangbusters for DS in Japan and it only sold 5.5 million, so I don't see how it's going to sell twice that much without some kind of price drop and extremely aggressive bundling, or some kind of DS Lite-esque hardware revision.
All three of those are possible, I guess. But even with the extremely strong software lineup for 3DS in Japan in 2013 I really think selling 10 million in one year is really pushing the boundaries of realistic expectations.