Fleming villians that have yet to be used by EON?
Just of the top of my head I can think of three(well technically four)
The Spang Brother's from Diamonds Are Forever
Von Hammerstein from For Your Eyes Only
Shatterhand(although an alter ego of Blofeld, could be used as that again or a stand alone villian) from You Only Live Twice.
Any I have missed? If they used any of these villians in a future Bond film it would probably be in name only.
They do seem to like mining Fleming for little easter eggs for the fans in the recent Bond films, so it wouldn't suprise me to see one of these pop up sooner rather than later.