-Killer Instinct Season 3 is incredibly likely. There's no explicit hint it'll be revealed at E3 instead of EVO or something, and it might be too early for IG to have anything since they're still wrapping up S2, but it's definitely coming.
-Lucas is being released for SSB4 on Nintendo Direct Day. The Direct will probably follow up with a new DLC character announcement. Rumors point toward Roy (Fire Emblem) and/or Ryu (Street Fighter).
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Rivals of Aether is releasing a new trailer revealing its 5th and 6th characters in
the middle of June. As an Xbox One (and PC) exclusive indie game, it might get featured by Microsoft at E3 in some capacity.