I put "not sure" because of 3 factors.
1. Will the PS4 have a pricecut?
2. If there is a pricecut, will Sony provide adequate stock?
3. Will there be a NSW+Mario Kart or Odyssey/BOTW/Splatoon bundle?
If there is no pricecut or stock is very minimal then Nintendo should win. I don't think either of the 3 big consoles will "dominate" though. At most I'd expect a 45/30/25 split or something.