The way I see it, Liu is like any of the other girls when sex was first introduced. She won't get more scenes until she's voted for the next update. And when she is voted, we'll get a dump load of story and scenes that are a little forced in the timeline of the game. Frankly, I don't know how many scenes would count as being 'enough'. I would love to see a solid dozen for each girl, but even then, I would just think "I also want to see this". One thing I really want is to see them add anal to all the girls. I think DarkCookie just dislikes anal...
Realistically speaking though, DarkCookie isn't using his Patreon funds intelligently. This whole game should have been completed a hundred times over in the years he's had it up, with a hundred times the sexual content. He's making over $90k a month. Hell, a sequel could have been developed right now. Merchandising would even be possible. But the reality is that he keeps his staff small so he can keep his income high, and we're the ones who pay the price for it. Literally. If he was smart, he'd be developing multiple games, hire more staff, and make up the difference in funds through the new games. There's no reason for his pacing other than greed and laziness.
Ultimately, what'll happen is that his patreon support will one day stop, and instead of completing the game with the funds he's saved, he'll just end production. The game now has an ending. It's arguably 'complete'. It's not satisfactory, but he could move on any time he wants to now and live off the subscription payments until people actually unsubscribe their donations. He'd keep the patreon page alive by barely adhering to the user policy and then just coast.