There were several characters that died in order to stop the Mad Titan Thanos from getting his hand on the Infinity Stones. However, despite these characters sacrificed their lives for that Thanos was still able to get his hands on the Infinity Stones and kill half of the life from the Universe.
Vision was one of the people who was killed by Thanos. Fans had already expected his death because he had the Mind Stone in his forehead and in order to get the Mind Stone out of Vision Thanos killed him.
But in Avengers Endgame our heroes were able to defeat Thanos and undo what he did in Infinity War. But Vision wasn’t killed by Thanos using the stones, therefore, we had to assume that he won’t come back in future Marvel movie until Disney made its announcement.
— Disney (@Disney) April 11, 2019
Disney had announced their plans for the upcoming shows on their Disney plus service. and in that announcement, they specifically mention a WandaVision series. In the tweet, they said, “@Marvel fans, unite! Elizabeth Olsen and @Paul_Bettany star as Wanda Maximoff and The Vision in a new #DisneyPlus series, WandaVision.”
So, we guess Vision isn’t dead. We don’t know how Marvel and Disney are going to pull that off because Iron Man died at the end of Avengers Endgame and originally Iron Man and Hulk both were involved in the creation of Vision. Therefore it would be very difficult for Banner alone to remake Vision if they are not going to an alternate timeline theory.