Cassandra sort of mentions her soldiers in the trailer, when she says they found the Inquisitor after the explosion.
I think there's a tension between these characters having their own agency and the game demanding (/requiring) that the player has even more agency. That's even more relevant when we're commanding an organisation with underlings and subordinates, rather than just a party where everyone is roughly a team of equals under the command of the player.
But if anything I'd expect Inquisition to err on the side of the player character being implausibly powerful and influential, to the point where experienced Seekers/Templars/spies/nobles are willing to defer to our commands for no other reason than we have a glowing hand and can save the world. That's par for the course in Bioware's games, obviously, but I think it's even more pronounced in Inquisition if we're going to command entire armies and fight wars.
There are still some unanswered questions about how much of a say the Inquisitor has in founding the Inquisition (do we seize power? Does Cassandra voluntarily place herself under our command? etc) but I'm completely not worried about Cullen or Leliana "disobeying orders" or advancing some vast Chantry conspiracy, except in the most extreme conditions. I think they'll be moderate characters who are "professional" enough to carry out the Inquisitor's orders. And I really do think the game will go to great lengths to make the player feel powerful, because that seems to be what people were wanting after DA2.