Quoting myself from several days ago on this thread:
There could be ways to have Vader survive. Edit out some dialogue alluding to his impending death, take out the scene with him leaning back, eyes closing, and going limp. Take out the appearance of his ghost, obviously.
It would make sense that he isn't at the Rebel's celebration. It could be left up to the viewer to decide what is going on behind the scenes: Vader undergoing repairs, possibly preparing to work as an avenger of sorts against the remaining Imperials peppered across the galaxy.
Something tells me Adywan won't be interested in this change, but it's worth discussing.