I'm not sure about "date" part, iirc only Yuna will have the relationship bar, or at least that were devs initial plans, maybe he will add some relationship to other characters, hut I would be dead set on it.
The "fuck" part, on the other hand, is more than certain, dev said himself that he has plans to add other characters fuckable, starting with sexy psycho, so it's just a matter of time....
Also glad you enjoy the game the way you do, but I have a feeling some kind of rebalance might find it's way in at some distant point, if devs view of the game stays the same as it was at the beginning
Cheers