Her antagonists are likely to continue being her antagonists for some time yet. Because when we talk about time in this game, it's only a matter of weeks in reality. But eventually, if the player continues to allow Anna to become more and more corrupted, then she will reach a point, where being abused is no longer a big deal. And she'll instead enjoy it so much, that she looks forward to it.
I think all of the main antagonists are now in place. There may be a few added who have short term roles from time to time, but I don't see us getting another regular antagonist like Jeremy, Patrick, Schmitt or Earl. And this idea, that she continues being reluctant and hating it, is totally at odds with her being gradually corrupted. Eventually, she either gets used to it, or her corruption stalls and she doesn't go any deeper down the rabbit hole. Because that's the nature of corruption. It only happens at all, because people accept certain things as normal, that in the past they would never have accepted under any circumstances.
The thing about the wallpapers, is that many of them will never appear in the game, or if they do, Anna will have changed by the time they eventually surface. The wallpaper you alluded to, depicts Anna as she is now. But in all probability, that version of Anna will no longer exist, even in only another week of game time. So even if such a scene were to appear, it probably would happen in a different way, to make allowances for changes to Anna's personality. Because one thing we can say with absolute certainty, she will change a lot between now and the end of the game.
I think a Dark version of Anna is coming eventually. And I can see it happening in two opposing ways. One where she refuses any cure that Schmitt develops for her condition, and totally surrenders to it, and ends up as a nympho cumdump and possibly as a hooker in the Red Light District. And the second, where she becomes a lot more dominant and even ruthless, and ends up taking over Sergey's gang, and maybe even becomes an antagonist herself. And they could be bad endings, where she never finds love, but instead becomes addicted to pleasure or power.
