From where we are in the story, the road to the end looks more clear than ever IMO. After Zou and Sanji's rescue (which will probably incorporate Whole Cake Island), we have Wano, which should be absolutely massive considering how long Oda has been hyping it up. After that, I believe that we have Elbaf, then an arc concerning Shanks, followed by Raftel and the foreshadowed Great War to conclude the series.
As for the supernovas, I think their story arcs will be incorporated into the stories of the remainder of the Four Emperors.
I would love to be proven wrong though; Oda's ability to twist and turn fans' expectations is one of my favorite things about One Piece!