Right at the end of the lat­est Nin­ten­do Direct had a sur­pris­ing reveal. Super Smash Bros. will head­ing to the Switch some­time in 2018. Nin­ten­do also showed a trail­er dur­ing Direct: 

There is no word on whether this is a new ver­sion of Super Smash Bros. from the Wii U, or a brand new title in the series. If port­ed from the Wii U, it could take the route of Mario Kart 8, arriv­ing on the Switch with more con­tent in a deluxe ver­sion.

You can see the rest of Nin­ten­do Direct, here.

Source: Nin­ten­do