There is a major battle between the town and the Upside Down in the finale of the fourth season of the show. The Duffers tease of an unhappy ending points to the idea that Vecna will be victorious heading into season 5, perhaps having officially destroyed the barrier between Hawkins and the Upside Down. The scope of the series has continued to grow, but it seems that everything will come back to Hawkins against the Upside Down for the final fight. Over the last seven years, Vecna has made this location his hunting ground and personal hideout, suggesting that the two are a package deal for defeat. The first volume of the season gave the teens the information they needed to understand Vecna's motives, but the characters may be in over their heads this time around.
Since Vecna is going to kill one of the main characters in the finale, the protagonists will be more focused on defeating him in the next installments. The ending of the second volume suggests that Vecna will be back in Hawkins in season 5, meaning that he will be more than just the main characters in this fight. The fifth season of the show would feature the characters figuring out how to destroy Vecna and the Upside Down as one, ridding the world of their terrors. The Duffers will not be repeating this formula in the second volume of the show, as the tragic ending will see multiple deaths and the characters will not be able to bounce back from a few months later.
In the opening scene of the new season, Eleven and the crew are still in the middle of the fight with the Upside Down. Vecna's true identity was revealed when Eleven recovered her memories from the Nina Project.
Adding to the notion that Vecna won't die is the Duffer brothers' tease that the fourth season won't have a happy ending. It is highly unlikely that the leader of the dimension will be destroyed before the end of the show. While Mike,Erica, andDustin were under the impression that Kas the Bloody-Handed had defeated their major foe, the campaign by Eddie Munson revealed that Vecna lives.
Vecna is the most frightening villain of all time, with the hint that he has been in control of the Mind Flayer and Demogorgons this entire time. The characters will not be able to defeat Vecna until they gain more power in season 5.
Vecna, a being who lives in the Upside Down, is the most dangerous threat to the characters in the fourth season of the show. The characters would be left with a less personally engaging and emotionally taxing fight in the last season if he were to die.
The role of Vecna/Henry Creel/One isn't a casting opportunity that is apt to be diminished to just one season, so the villain's return is more than probable. It would be a near-impossible task to find a villain that could instill the same fear and anxiety in the characters as a more accessible villain. WhenDustin tried to defeat Vecna again in the game, he was unsuccessful, suggesting Eleven won't be enough to kill Vecna in the finale. The season finale of Stranger Things usually ends with the characters defeating the Upside Down's villains, followed by an epilogue in which they adjust back to normal life.
Vecna is going to take over Hawkins with the Upside Down in order to take as many victims as possible. He is the first Upside Down villain to have a purpose other than destruction and domination, with a human origin that personally connects to and attacks the heroes of the show. Kas may be referring to Eleven banishing Number One to the Upside Down, as her flashbacks depicted her with blood on her hands to symbolize how removing One's Soteria chip inadvertently aided his massacre of the children in Hawkins Lab.