Pokemon may not have as much of a sales boost because they already did release a pretty high profile Pokemon game last fall, Pokemon are important characters in Smash as well, and generally speaking Pokemon fans tend to like other Nintendo IP too so it's not like they just sit there waiting for Pokemon to release.
I would forecast 18 mill with the internal expectation to sell 19+ (but not saying this publicly) if they have a nice new model this year and maybe a price cut too.
If they want to be selling 20 mill/year+ they will have to embrace the Pro/X model that Sony/MS have. You need to have two models that can sell concurrently (rather than just a revision that replaces the old model) to get that kind of a sales boost. I would say both sales of PS4 and XB1 would be 15-25% lower what they are right now if they didn't have the Pro/X model.