I really really really hope Cullen is not a NPC 'mance. I didn't like Traynor or Cortez's short, full of nothing romances at all, and would be really sad to know we finally had Cullen and they did that NPC nonsense to us. Reduce him to barely a few spoken words and romping. BUT what gives me hope is GE saying Cullen has a lot of dialog in game and a big part +raunchy/sexy 
I appreciate the sentiment. The non-follower romances do seem less fleshed out and less satisfying. For one thing, I like to play *all* the romances, so I'd like to be able to appreciate Cullen on the playthroughs when I'm romancing someone else.
Honestly, I would not worry too much. They did not explicitly state "follower romances" before, but they did not explicitly state otherwise. There have not been any non-follower romances before in a Dragon Age game, and they were not well received enough in Mass Effect to make it seem like a viable crossover.