Twitter looks like its genuine, unless some sicko (who also follows Tarantino’s work) is impersonating her with so much information. Casting her seems plausible since Quentin is on a '40s movies kick lately, not to mention Bacall worked with his favorite Howard Hawks on two of her best movies… Also, IB was shot in Berlin where a lot of that novel seemingly takes place so maybe he already made some preplanning or location search since he obviously loved working there.
Of course it could all probably be a hoax, but how cool would it be to team-up Hopper and Walken with Tarantino’s writing again?
EDIT:
“The traitor from London has flown to the East. It is Bernard Samson’s wife, Fiona. He is now a marked man. His children are under armed guard against abduction by the KGB. MI6 wants revenge. They see their chance when intriguing news comes from Mexico.”
http://ftvdb.bfi.org.uk/sift/title/417138
