Firmware is always being tweaked; I would expect Leica to continue tweaking the M8, with firmware upgrades every year or so. Both my D2x and R-D1 have had post-sale upgrades. It's no big deal. Which means that at some point, Leica can simply pronounce the camera ready for sale, even if they realize it may not be in its ultimate form. I expect now (from what Sean has said) that it's very, very close.
If there's any problem at all, it'll be in the physical production of the thing. Even a company as big as Nikon can sometimes be caught off guard, as with the D200, where they apparently were not able to keep up with initial demand, and there were delays in getting the necessary number of cameras to the market.
The Leica seems to be generating a lot of buzz, and if the demand really pops, some people may have to wait. But I expect the first ones to be delivered in November, just as they say. I'm not sure that if someone were to go to Leica now, and ask when he could get a camera, that Leica could tell him for sure.
JC