It could be done with one short repeatable cutscene (similar to the kiss scene you currently get with most romances) that can be triggered but does not lock you in the relationship.
They didn't even have time to code in that little cutscene for Solas (let's face it, as much as the game and Solas' hidden nature and conflict over his feelings suggests that the whole romance thing was rather subdued, the reason we didn't get as much interactions with him was veeeery likely budget and time contrains), hence I doubt it was anything they've even considered.
Given the length and breath of the game, romance interactions would still be, I estimate, 5% of the total gameplay. It doesn't have to be a full-on dating sim, just make the dating that is already there a tad more open to creativity.
It's still 5% or more percent completely wasted in most playthroughs. There's a considerable resource budget they already put in varying interactions an romances in the first place, so...
Those are great options, I've had fun with them, and yes, it's enough. Still, I see things that could be made better and point them out, without even expecting anyone would eventually adress them.
Well, lets' be honest here - we're not playing a nobody here. The Herald Of Andraste is a sort of Thedas new and most talked-about celebrity, therefore such things would be hard NOT to note, story-wise, even among companions... People DO note when an ally is being romanced after all, no matter how private and innocent that romance is, AND Josephine reveals that there are craziest rumors about who's Inquisitor with anyway xD
In any case - the only thing people can count on is likely Citadel-like DLC, but we have no guarantee they even consider creating something like it for DAI.