Another sad day for the film world. The part that makes me more sad is that there is no heir apparent. While there are plenty of great young filmmakers, there is nobody else making films like Network, 12 Angry Men, The Verdict, etc..., etc....
Lumet also appears to be one of the last of his generation. Off-hand, I cannot think of another filmmaker from his generation that is still around.....let alone one that worked right up to the end. "Before the Devil Knows You're Dead" was extremely underrated.
Rest in Peace Mr. Lumet. Your work has already stood the test of time and will continue to do so.