As Dragon Age 4 deals with the outcome of Solas' plans, there's likely to be more new content introduced to the world. One of those seems likely—The Executors—as even Solas appears to be wary of the "Powers Across the Sea." However, what these powers are or who they are remain to be seen, something DA4 should correct.
First 'appearing' in Dragon Age Inquisition, The Executors appear and reference themselves as "those across the sea" or sometimes as those in service to the "Powers across the sea." They're a shadowy group, never once meeting face to face with the inquisitor, but instead watching the player character and their inner circle closely. Based on the language, it seems the Executor's primary location or home will be across the Amaranthine Ocean, outside of Thedas, and therefore mostly unrelated to the current and on-going politics. To encapsulate their mysterious, sea-oriented motivations, the Executors who an upside down triangle with two wavy lines (the ocean) through it.
In War Table missions, this symbol begins to appear at Inquisition camps across Thedas. Either Leliana or Cullen can check it out, but either way, the message is clear: The Executors believe that Corypheus' actions even threaten them, trust the Inquisition to deal with the treat, but are watching the situation closely. However, the communications are quick to point out one key fact: the Executors and the Inquisition are not enemies "for the moment." Choosing Cullen results in more of a standard approach, but Leliana will track an Executor Agent all the way to Caimen Brea, a potential Dragon Age 4 location in Tevinter.
Their latest appearance is in Dragon Age: Tevinter Nights, where an Executor agent is in attendance of a meeting of Thedas' best spies. Charter, a spy for the Inquisition, is tricked there by Solas, who petrifies the Executor before they share any information. Charter sees the Executor, although they are covered head to toe with dark robes and no openings. The Executor's voice could have been "male or female, young or old," and Solas warns Charter not to trust them. This has two implications: the Executors are indeed a new race, as this doesn't really fit any Thedas culture that comes to mind, and that Solas is aware of them and wary of them.
Despite the heavy emphasis on the Executor's location across the sea, it's worth mentioning that the Executors are not the first culture to be identified from across the sea. The Kossith—the predecessors of the Qunari—landed in the Korcari Wilds and were how the Darkspawn created Ogres. They were killed off, with the culture returning centuries later as the reformed Qunari, yet that is one big question: why did the Qunari come to Thedas?
The Qunari's origins are entirely speculative, as they have not yet been elaborated upon fully in game, but Iron Bull says he believes the Qunari left because they had to. If they had to leave the lands across the Amaranthine Ocean, that's a huge implication because then the Executors are at least more powerful than the Qun. They don't seemingly balk to much, but going a little deeper, Iron Bull is also under the impression that the Kossith and Qunari do not look anything alike.
And it's known that the Kossith, prior to the formation of the Qun, were animists—they worshiped nature, believing everything to be animated and alive. It's possible that these Executors are another splinter of the Kossith who maintained their ancestor's ways, worshiped the sea, and eventually overtook the Qun. That is, indeed, one possibility to explain the origins of the Qun, the Executors, and more. But Dragon Age: Inquisition's Corypheus threw another wrench into the equation.
Just as Corypheus' remarks about the throne of the Maker being empty and the Golden City being blackened when he got there undermine Chantry thought, potentially connecting the Blight to the Veil, Solas, and the Evanuris, Corypheus will make an interesting quip if the Inquisitor is a Qunari. In the final fight, he says something to the effect of "your race isn't a race, it is a mistake!" But this begs the question of how Corypheus would know.
After all, while Corypheus may be an ancient Darkspawn, he was a Tevinter Magister before that. The Kossith didn't appear until The First Blight though, so as far as Corypheus' freedom in the world, there's almost no way he personally knows what happened. It's possible that his connection to the Darkspawn, to the Ogres who are created from the Qunari, gives him the knowledge of the Qunari's origins, but that also begs the question of why keep it a secret. Corypheus seemingly tries to use this knowledge to belittle a Qunari Inquisitor at the very end of the game, while not doing so before, and if Corypheus was aware before, then so too does it seem Solas would be.
If Solas did not share it, then it was either too important or too ground-breaking to share, or it was a non-issue. Without more evidence, it's hard to say for sure, but it seems likely that Dragon Age 4 will introduce and explore these Executors, who will have potential ties with the sea as a god of sorts, Tevinter for some reason (or the Darkspawn, either way through Corypheus), will have some uncaring connection to Solas, and perhaps most important, will connect the to the Kossith and the Qun. Only time will tell.
Dragon Age 4 is in development for next-gen consoles.