It's probably going to go over modes, stages, and probably a new character or two. People who thought we wouldn't get another Smash Direct after the E3 Direct must not understand that this game has a much shorter marketing cycle than Smash 4 and thus needs to show a ton of information in a shorter amount of time. Smash 4 had a solid year to show things, ramping up its marketing in 2014. There were several Directs where they had a Smash character reveal at the end, DLC included in 2015 Directs. Like, the Smash Direct they had before Smash 4's release wasn't too long from a previous Direct where we just had Smash info dropped in it iirc.
They are probably going to have this Direct and then depending on how much info. gets spilled here will determine if it seems like there's enough for another one around November before it releases or if they'll just continue to drip feed into the next general Directs like they did with Smash 4.
Still, the point stands that shorter reveal to release = more info going to be dropped in a shorter amount of time.
