If there's 8 romances, 5 are confirmed, and 1 is an outside romance, that leaves 2 more from the companions that are left. So:
Females - Vivienne
Males - Cole, Blackwall, Solas, Varric, Iron Bull
Seems less likely that Varric's a romance at this point (drat
). I'm not betting on Cole being one at all. Seems Iron Bull will bed anything that moves so he's likely 1 of the 2 remaining. That leaves either Blackwall or Solas. If Blackwall is dedicated to the Grey Wardens, he might not have time for the Inquisitor's affections. If Solas is dedicated to his cause, the same can be said for him. Vivienne seems less and less likely but she's still a possibility.
So toss up for the remaining 2 seems to be Blackwall, Solas, and Iron Bull ... and maybe Vivienne.
Then again, the outside romance could just be a fling with a one time deal and doesn't interfere with the other romances with companions/advisers ... but not holding my breath. Iron Bull could also be potentially be a fling and not be a "full" romance (in that marriage and what not is not apart of it). Wishful thinking. Honestly, my bet's on Solas and Iron Bull being the other 2 companion romances, though.