If he weren't doing so many Hollywood productions already, I would half suspect that Sharlto Copley of "District 9" fame would find himself on the shortlist.
For the longest time since seeing "Inglourious Basterds", I thought EON would book Michael Fassbender to play the villain, but then his star actually rose and he became an A-lister in his own right. Plus he just played Magneto. Still, with Oscar-winner Bardem having played the last one, I suppose anything's possible.
Dave