You know, I really hope that the real Empress is still alive. Either still inhabiting the body but is dormant, or maybe possessing the MC's body from Earth. I find it to be quite sad thinking that she is just gone after being turned into something she wasn't, with the entire Empire having the ruined image of her in mind. I kind of doesn't want the body of the MC on Earth to be over either. I kind of want a redemption arc there. Hell, would be funny if the Empress did possess the MC's body and goes on a redemption arc, eventually bringing the Korean Dynasty back to life as the Empress and leading the charge of expanding the empire. Would be quite funny. How this timid and bullied girl that was a slave to her work, suddenly takes on a no BS attitude and becomes a leader.
I do kind of want them both to be alive in this same world. I don't know, maybe have it so if the Empress ever has a child, that it will be the MC or Empress inhabiting the child now. Then again, it's honestly weird to imagine the Empress Pregnant. I just can't imagine how that'd look with the badass-looking character design of the Empress.
Though, I feel it might be funny if the Empress returns to her body, just to find out that she is Pregnant. I feel this could be an entire manga. That genre of stories where someone possesses the Villainess. But this time the VIllainess returns to her body, and now has to deal with the changes the previous inhabitant has done. Like she still has her bad attitude but is now dealing with the reverse harem of guys that started following the VIllainess body.