I wouldn't be surprised if Kunlun itself was destroyed or heavily compromised during this war. Kunlun and Penglai both feel like rigid relics of the past, not fit for handling the present. Maybe, by the end, A-Ting will create a new Sect that gets rid of the old notion that the mortal and immortal worlds should not mingle with one another, and she will lead an effort to arbitrate and protect the mortal world. But for this to make sense, it could only happen once the spiritual energy draining situation is solved, because otherwise only descendants of cultivators can have a spiritual root, and the mortal world should be taken care of by its denizens. The story would probably need to adress this point and restore the old behaviour of humans being able to cultivate, too. And that is probably where her twin brother would be most relevant... But if he ascends, i am afraid the twins will never get to be together. They still haven't properly met at this point, aside from the 3 seconds they saw each other in the dead zone.