The devs have stated on their tumblr blogs that they won't be making romance DLC for the other characters (since not only would it be extremely hard and costly, but they've already decided to write those characters just as friends)
i genuilnely find it really cool that i´ll kinda grow with the game (by the year this comes out i´ll be a legal adult, so it´ll genuinely feel like the characters grew up with me)