S.T.A.L.K.E.R. 2 seems to be coming in 2021 according to a post on ResetEra.
So far, the STALKER franchise has 3 titles: S.T.A.L.K.E.R.: Shadow of Chernobyl; S.T.A.L.K.E.R.: Clear Sky of 2008 and S.T.A.L.K.E.R.: Call of Pripyat of 2009. The nuclear accident and another odd event some years later have caused a number of terrifying mutants and unusual phenomena to spring up in the zone.
CEO of GSC Game World Sergei Grigorovich announced in Facebook that is now being developed computer game S. T. The game is set in a world where there was a second nuclear disaster in Chernobyl. However, I'm sure in due time we'll learn more about S.T.A.L.K.E.R. 2 and the platform (s) it will be playable on. A large size banner can be seen on the official GSC Game World website along with a direct link to the Stalker 2 website (http://stalker2.com).
A few moments ago, GSC Game World announced on its official site that they are developing Stalker 2, a title that had a previous phase of creation more than 7 years ago and was canceled in 2012.
S.T.A.L.K.E.R. 2 website landing page. A website cropped up (http://stalker2.com) and the official GSC Game World website states that the game is now in the works.