Even if there is a b&w M8 at some point, I doubt very much that it would be 33mp.
That particular pipe dream seemed to stem from the "rumor mill" poster's fundamental misunderstanding of how a digital sensor works. He assumed that the M8 contains three 10mp sensors -- one each for R, G and B -- so if you eliminated the color filters, you'd somehow have a 30+mp camera.
In fact, the M8 contains a single 10mp sensor; individual pixels of that sensor are filtered for R, G or B. The G and B values for each R-filtered pixel are estimated based on the adjacent pixels with G and B filters; likewise for the other colors.
Even with the filters removed, you'd still be getting only 10 mp of luminance data, which is what you need for b&w.
An M8 with no color filter mosaic would have slightly higher light sensitivity, but that would be its only advantage. (Even a b&w version would need some filtration anyway, to give its sensor something approximating panchromatic sensitivity, so the advantage might not be as great as you'd think.)