3DS is doing OK, but Nintendo has Japan to back them strongly and once they took away Monster Hunter from Sony, it was like taking candy from a baby. Once they got the price to sub-$200 they were OK. It just won't have DS levels of success but it can do OK in the West.
Wii U I think is in big trouble though, it's a system not quite enough for casuals, and not quite enough for hardcore either, at its core its flawed fundamentally and I don't think even Mario Kart or Smash Bros. will fix that.







