They certainly could have built an AF module into is like the Contax G series of film cameras. Plenty of room in the M-Mount for electrical contacts, and a new series of lenses in M-Mount to use them. Nikon made an AF version of the F3 in 1983, and continued to use the F-Mount with AF cameras.
Such a camera would broaden the appeal.
CMOS, Liveview, Video, Autofocus- in an M series camera "go with the flow": maybe Leica is betting it would pull in new users. The M9 Monochrome "Buck the Trend"- will make many of the core Leica users very happy, and maybe pull in some new ones as well. My money is on the M9 Monochrome. Literally.