I think 3DS will have the same problem of psp it will sell in first years very well but software will be low exept sale of mario and pokemon and it last years the hardware sale will fall like the psp and monster hunter will never be an exclusive.
Monster hunter=psp ,the game will never sell more in 3ds then in psp.
In other hand i think this ngp will be much more succesful then psp i don't know why the magority think the ngp will do like the psp or worst then that.
This time sony has more suport for developper then with the psp sony has annonced monster hunter et call of dutty and will appeal casual gamers with game like angry bird and little deviants.
PS4 - over 100 millions let's say 120m
Xbox One - 70m
Wii U - 25m
Vita - 15m if it will not get Final Fantasy Kingdoms Heart and Monster Hunter 20m otherwise
3DS - 80m