Once production begins or at least draws closer, more story points should begin to be revealed.
Beginning production in May will give Wan and company nearly a year and a half to go through filming and post-production ahead of Aquaman hitting its newly-planted release date.
With many of the big roles already filled, there are still plenty of casting announcements that will be made over the next five months ahead of production.
Also, Black Manta may yet be involved in a villainous role as well, so there should still be a number of high profile roles to be cast.