In a recent interview with the French publication Le Journal du Dimanche, Fincher, who also directed several episodes, was asked about Mindhunter’s future. Regarding the possibility of season 3, Fincher explained that the show is a costly investment for Netflix that is not worth the risk. Here is the quote below via GamesRadar:

“I’m very proud of the first two seasons, but it’s a particularly expensive series and, in the eyes of Netflix, we haven’t attracted a large enough audience to justify such an investment. I don’t blame them, they took risks to launch the series.”

I think it’s safe to say dead, as much as I would love to be wrong