In the closing moments of the show, Roseanne reveals that she’s been writing a book about her life, which is what we, the viewer, have been watching since Dan survived his heart attack. Except, he actually died. And the Conners never won the lottery; Mark/Darlene and David/Becky are the couples, not the other way around; and Jackie is gay, not Bev.
Roseanne could continue with the Healy brother swap for ABC’s upcoming eight-episode revival (it wouldn’t be any weirder than Second Becky playing Not-Becky), but according to TVLine, Dan is “very much alive.”
Also, the new batch of episodes are “going to pretend the finale never happened."
"An insider says it’s probably safe to assume that pretty much “everything that went down” in the series finale will be ignored when the revival launches in Spring 2018." (Via)