Killer Instinct will indeed feature fan-favourite character Chief Thunder, sporting a new design and grapple-based moveset.
In a reveal trailer posted to IGN, which you can check out below, Double Helix discusses the difficulties of presenting a character which was designed in 1994; studio head Patrick Gilmore said that in 2013 you can't just "lean in" on Native American culture and tropes without being mindful of social expectations.
That said, he was "in the roster from the moment we started planning this game", so the developer has redesigned him, modernising his look but keeping his formidable feel. Chief Thunder is a grappling character with mostly ground-based play, and twin axe weapons. The video goes into detail on the character's moves, which nod at some classic Killer Instinct specials.