I can't believe we're having dialogue about game modes, when APB is practically unplayable right now…
From a business standpoint, "Battle Royale" IMO is the best, if not only game mode that should be implemented. Like it, or hate it, (I'm not a huge fan myself), it's popular right now, and will attract people to this game, which will be needed after the excessive fail that has been going on since the LO purchase. If you incentivize it for "BR" players to do missions, (unlock skins, clothes, etc..), you will have a chance at strengthening the population long term.
Why get rid of Open Conflicts?...just make all the servers OC. This whole match making nonsense is played out. Get back to basics...you K' up...you play.