It interests me to note that a lot of the points being raised here are not really against the M8 specifically, but against digital cameras in general. Yeah, they're battery-dependent. Yeah, the sensor stays locked up inside the camera (unless you spend the REALLY big bucks and get something like a Hasselblad H2... but guess what, the sensor in that isn't "full frame," so there's a crop factor on your 80mm lens... guess it really must be a piece of crap, huh?)
So, people who don't like digital cameras are never going to buy an M8 no matter how good a digital camera it is. Does that mean it's going to be a failure? Well, the vast majority of the photography market has gone to digital, and the vast majority of the upper end has gone to 35mm-esque DSLRs such as those from Canon and Nikon.
Until recently, the people who use those systems (and whose investments in them might make the M8's price tag seem like a drop in the bucket) were basically locked out of using an RF camera even if it would have had utility in their photography, because it would have meant going back to a film-based workflow for part of their shooting. That's just not practical for the average high-productivity digital shooter (as I found out the hard way when I tried to keep a "hybrid" workflow going.)
A lot of these big-dollar DSLR shooters are photographically sophisticated enough to know that an RF camera might have some advantages for some parts of their work. But before now, there was no way for them to buy into these advantages. A lot of serious photographers are pretty conservative, and a camera from a non-camera company (the R-D 1) probably wouldn't have been persuasive for them. The M8 won't have that problem -- it's about as conservative as a digital camera can get!
The more I think about it, the more I think we will see a significant number of high-volume DSLR shooters pick up an M8, maybe just to use one or two wide and/or fast lenses. You've seen the gigantic bags some of these guys lug around, right?... adding an M8 and two lenses would barely add a bulge.
Will it save the company? I don't know. Will it be the best-selling M ever? Probably not -- the M3 had the advantage of being on the market for many years, and at the height of the RF era, so it'll probably never catch up to that. But will it sell fast, and will it bring new users into the RF fold? Yes, I think it might! I suppose that's good news for me even though I can't afford one.