He might be interesting to have around, maybe as a DLC or as a side quest... but I just... EH about it all as him as a full blown party member. Maybe if we got Rhys and Cole was kinda... there in addition to him. Like having him serve as an invisible to all but Cole ancillary character... Like Dragon Age's version of a Tali's turret.
"Get him, Cole!" *Cole materializes as he stabbinates someone attacking Rhys only to fade back into invisibility*
The problem with saying he could be a DLC character is that he can't be a DLC character. Either he's one of the nine companions or he isn't going to be one at all--he might appear in the game even if not a companion, but I think his story deserves more time and effort than just a side quest. He's a very interesting character, in terms of what he is and how he ends up at the end of Asunder.
But, yeah, the devs have said there won't be any DLC characters at all this time. I guess all DLC will be weapons and quests. No new companions, because people complained they were having to pay for unlocking characters that were already in the game. I think the real solution here is to find a way to design the game so that the number of companions is able to be modified, rather than requiring a framework to already be in place. But that's just me.
There is a possibility he's the "deceptive wax fruit" the devs mentioned when naming characters after food. I would have thought "surprise meatballs," because he isn't what you'd expect, but "wax fruit" or "plastic fruit" would describe him pretty well--he looks real, he seems real, but he isn't. In fact he's a poor imitation, because he'll never be human just like wax fruit will never be as tasty as the real thing, doesn't smell like the real thing, etc.
Either way, if he doesn't appear in DA:I, I hope he makes it into the next game, or one or more of the next novels.