Is this new?

[NotAnAdmin]

So it seems that you can cancel the sliding animation of a dash with a fsmash, but only a fsmash. I've tested this with only Ike, Falco, Capt Falcon, and Luigi. Luigi didn't slide like how I wanted him to, a real disappointment.
It works like a pivot grab but except you use the c-stick instead to begin a fsmash.
It could be used as another option to mind game your opponent.
Doesn't seem to have any other use, unless you read a roll or something it could be a quick punish.

 

[Firehyphen]

Im pretty sure it works with up smash as well.

 

[Terrazi Terrajin]

Pivot up smashes from brawl have indeed returned as well.