<Update: The 1C blog has the closure.>
A rumor has popped up that S.T.A.L.K.E.R. developer GSC Game World founder Sergei Grigorovich was going to shutter the studio and that S.T.A.L.K.E.R. 2 was canceled. The company issued a denial on Twitter, stating "No we have not closed GSC or cancelled #stalker2" - but the tweet was itself deleted, leading to even more speculation.
If that weren't strange enough on its own, an even wilder second-hand rumor states that S.T.A.L.K.E.R. 2 generated "interest from one of the (Ukranian government) security agencies" regarding the Chernobyl area. which may have played a part in the suspected closure. According to one news source, "Given the sensitive nature of the Chernobyl area in which the series is based, government intervention would not seem inconceivably far-fetched."
GSC Game World employs roughly 40-50 people. Stay tuned for further developments in this bizarre story.