The Duffer Brothers said that one of the final shots of the show was meant to show the idea of war and a supernatural war coming to Hawkins. Will made it clear that Vecna is not gone for good and that the stakes will be raised in the final season of the show. Since the Duffer Brothers talked about how Empire Strikes Back influenced their choices in Stranger Things, there's a chance that they will reference Star Wars in the rest of the show. It's not a foregone conclusion that Eleven will turn to the dark side, but it could make for a very interesting conflict in the upcoming season.
The Duffer Brothers discussed the ending of the series after the finale.
The immense popularity of the show means that it could follow in the footsteps of Star Wars and become an extended franchise. In terms of tone and feeling, Empire Strike Back is the closest thing to the Star Wars movies that has a dark tone. Vecna may try to turn Eleven to his side if there is a similar trajectory to Return of the Jedi. In Return of the Jedi, the rescue plan was to get Han from Jabba the Hut and unfreeze him. The consequences of season 4 are even more dire now that Eddie and Dr. Owens are dead.
One of the biggest questions after the end of season 4 is whether or not Max will return. The Duffer Brothers have an idea for a spinoff set in the same universe.
The Empire Strikes Back changes the trajectory of the original Star Wars trilogy when Darth Vader reveals that his son is a Jedi. This sense of brooding conflict was inspired by the shot in Empire Strikes Back where the characters look at the galaxy outside of a spaceship window. In season 5, it's possible that the influence of Star Wars goes beyond references.
Vecna's revelation that Eleven is to blame for his plan's success only makes the connection worse. The unbreakable bond between hero and villain means that Darth Vader wants to turn him to the dark side in order to rule the galaxy together. There's a dark part of Eleven that she is in constant conflict with, and Vecna could try to corrupt that in the final season. "We always wanted to do an Empire Strikes Back ending which we tried to do with Season 4," they said. The show is not afraid to wear its '80s influences on its sleeve, from Mike's gang wearing Ghostbusters costumes on Halloween to Eleven being the group's own human.
He's Darth Vader's son, but his conflict between light and dark is the crux of Return of the Jedi. By sharing this surrogate father, one could say they resemble siblings, since they're not quite father and son like Darth Vader in Star Wars. In the second season of Stranger Things, Eleven was tempted by the path of revenge that Kali set for her, but she chose against it. The Duffer Brothers wanted to create a "sense of loss" in the end of the show. After losing her powers at the end of season 3, Brenner helped Eleven regain them.