During the Nintendo Direct presentation today, Nintendo teased an upcoming Smash Bros game simply titled "Smash Bros".
In a rather dramatic trailer mostly involving the squid kids from Splatoon and a very agressive looking Mario. Nintendo finally confirmed the long rumored Smash Bros title for the Switch.
As of now there are no further details of the game outside of the release date happening sometime in 2018.
https://www.youtube.com/watch?v=w3Gt42kVgCw