Yep, Smash certainly was always going to be one the best seller of the year. Nintendo advertised it as the Event Game, the content and the reviews along proved that it was and those sales are pretty great.
Going to be very fun to watch the legs on this one, espicially with the DLC Characters probably bringing in entirely brand new fans with wild unexpected character choices. Probably going to be one of the top 5 sellers of the entire switch lifespan when all is settled.
2019 is going to be really big for Switch, Continued sales of prior nintendo games, Smash DLC with (most likely) wild third party picks, Fire Emblem, Animal Crossing, A Proper Mainline Console Pokemon game, and probably something else that hasn't even been revealed yet (Mario Maker Switch maybe? And also possibly Bayo 3 and Metroid Prime 4 releases as well? They aren't going to sell as well as the other titles, probably come in lower than Luigi's Mansion 3, but they'll still sell well). Add in possibly a new rumored hardware revision and maybe a price drop on the first model and woof... gonna be a big one.