xMetroid on 09 August 2018
I don't think any switch game will top 25 million in less than 2 years since their main selling franchises aren't out yet (except from MK but it's a port so there probably a lot of people that didn't bought it twice).
Think Smash can make it, maybe a future animal crossing, 2D mario and the next pokemon game. But that's not coming out soon enough tho.
I hope BoTW will make it in the top 10 before the end of the decade.
