not really that hard to predict at this point for 2017, it's quite obviously killing it this year, quite possibly will beat PS4 for top console of the year in sales.
Going onward is a mystery though as at this point in time we have literally no idea what will be releasing for the Switch in 2018/2019
2017 with FE Warriors, SKyrim, Odyysey, Splatoon. 2017 is settled
Prediction in February before launch and in June 3 months after launch are not same things. :D But actualy its still hard to predict at this point beacuse stocks problems, we saw lines in Japan for Switch 3 monts after Switch launch, so for long we will have stock issues, beacuse they definitely affecting currently on sales. Saying that if Nintendo has enough stocks there are chances that they can sell 4m in Japan in this year alone.
I have pretey good picture about 2018. for Nintendo games: Fire Emblem, Pokemon, Animal Crossing, Smash Bros, Retros game, Next Level Games game, posible Pikmin 4, posible new Metroid Prime...2019. is to away to currently think about possible lineup for that year when curently for now we have only one 2018. confirmed game.