I don't think strikes and crucible will need pre-made teams but as always everything is easier with teamwork. I think the team play is stacking supers so the team can recharge and maybe more specific roles to complete specific endgame tasked. I don't think it'll be super important to fill those rolls be I do think it'll make activities easier, match game modifier comes to mind. I'm a long term "fanboy" who happens to like grind based games so I'm looking forward to this "hardcore second job" Bungie has built.