I don't think the discussion of genlock origins or the merits of the redesign (I already told you, I hate the new hurlocks and the new armor) is going to get anywhere. So let's refocus on what began this discussion.
Why do you think it's unlikely that these figure are dwarves, ghouls or not?
So be it.
It's because of the context of video's presentation that most convinces me.
The trailer is mostly about exploring the deep roads, facing darkspawn and facing some giant rock monster. Perhaps it's just the engine, but there's something about those enemies that strikes me as being directly darkspawn related.
They seem stocky, but they appear to be as tall as humans and move in an aggressive, yet robotic manner. I thought that I even heard those figures growl. Plus, they're introduced right after we see the ogre and the emissary which heavily implies that they're darkspawn related if not darkspawn themselves. Plus, if you closely at the visor, you see hints of a monstrous face denoting that of a darkspawn.
Considering that we've seen darkspawn scavenge the armor of the dead, it's not implausible for these darkspawn to have killed Legionnaires and took their armor as their own.
I doubt that they're ghouls as most ghouls get weaker or don't live long unless treated. There are exceptions and how long someone survives varies from person to person, but I doubt that a ghoul would willingly become a shock trooper for the darkspawn unless they were being directly controlled by a nearby emissary. True, tainted animals attack people, but they're normally acting on pure savagery and instinct unless being actively controlled and tamed by the darkspawn. And keep in mind that the Carta thugs that took the darkspawn taint were being controlled (and empowered?) by Corypheus.
They could be Kal-Sharok Dwarves, I won't dismiss that possibility. But they seem a bit "tall and big" to be dwarves. Or maybe these dwarves from kal-sharok became taller due to evolution and needing to adapt to survive isolation. That still doesn't explain why they would attack the Inquisition since the dwarves of Kal-Sharok have worked with the Inquisition before. Unless these are rogue dwarves.
All in all, I bet that those figures are darkspawn. Maybe not genlocks, but definitely darkspawn.