Currently, it looks like there's two different game modes. A Descent style "Heroes vs. Overlord" campaign system, and a 1v1 tourney style skirmish mode. Personally, I'd like to see a fusion of the two to fill the gap left by Necromunda and Mordheim.
Would much rather see people doing local campaigns where they level up their Imperial or Rebel or Scum squads than see yet more obsession over tournament meta.