This series is the Game of Thrones of Netflix strangest thing which the series started in 1980 to Hopkins Indiana with Hopkins lab that opens the gateway to the upside down a veil of Shadows like to mention that holds the most dangerous creatures codenamed after know DND characters and even if the gates been closed twice those with dangerous ambitions still mess with those that can't be controlled like the demogorgon an an alpha predator and the mind flayer a class Alpha. If it's been open for more than a year it will affect anyone it will find a use for like making a physical body.

As far as I know if there be a movie after final season it's going to be a Pennywise situation in the 2000 if you ask me.