My Predictions:
September: Nintendo Direct, ends with a trailer for the Pokémon newcomer (Tapu Koko or Incineroar), no other Smash news than that.
October: Smash Direct, opens with Bandana Dee trailer and showcase, Isabelle and Impa as echoes, reveals Spirits mode, showcase of other modes (HRC, Break the Targets, Target Blast, Multi-Man, Master and Crazy Orders, Challenges), ends with Skull Kid trailer.
November: Final presentation, reveals Shadow and Ken as echoes, details Online, Geno trailer and showcase, ends by showing us the full character select screen and All-Star + announcement of DLC happening.
Edit: I fully expect to be wrong, because Sakurai isn't that easy to figure out.