Liam Robertson, well known for his contributions to Unseen64, and Did You Know Gaming has made an interesting tweet regarding Smash Bros. on the Nintendo Switch. He thinks there will be new characters in the Switch version of Super Smash Bros. He did not say what kind of characters would be added in, but did note that there won’t be many additions to the lineup from previous iterations.
Many fans would expect this as it would be weird for Nintendo just to port the game over and do nothing. Also keep in mind that Nintendo never came out with amiibo for some of the latest characters, so they could be waiting until the Switch version to come out then launch more amiibo.

I guess we're leaking stuff, so okay, there will be some (not many) new characters in Smash Bros Switch.

— Liam (@liamrobertson.bsky) (@Doctor_Cupcakes) December 6, 2016