I personally think that like the GBA, Nintendo will announce and release its successor sooner which I personally believe will be a smart + dedicated hybrid of sorts. Of course it could be a revision of the current 3DS which means that its sales will still count towards the 3DS, or it could be a new console that is backwards compatible. However, assuming Nintendo releases a new system between 2015-2016 (which is my personal prediction) then I believe that the 3DS will sell around 65-75 million units in its life time, coming short of PSP.