I doubt that second hand digital M camera prices will be dictated by collectors in the near future (except for the exotic incarnations). Those collectors should find a ready supply of mint, in-box digital Ms over the next few years.
I think that from a purely practical point of view, relatively recent digital Ms will always be more expensive than the commonly found film Ms, simply because you don't have to pay film development costs and more people shoot digital these days so they are more desirable for people actually using the camera. Of course, for all "shooter" quality standard bodies, price within a range will be determined by how used they look,and roughly how many exposures you can expect before failure. This last point is something we have no idea about right now.
I think another key variable will be how soon the competition can make an equivalent size SLR/EVIL with a 1.3 crop or full frame sensor. If they can trim down all of those "unnecessary" electronics and get down to the size of an OM1, then one of the main selling points of a digital M will be neutered.
Right now, you can choose between the following cameras still in production:
- a film M or CV Bessa limited by the chemistries, development costs, and slower post processing of film,
- an expensive digital M,
- a big heavy complicated expensive dSLR with massive lenses,
- or an interchangable lens compact camera with a heavily cropped sensor and electronic viewfinder.
At least with the Leica Ms, you know that Leica will continue to service the ageing digital models, as they have done the Digilux 2 for example. This will allow them to retain some value as the potential cost of buying a dud is recoverable to sme degree.
I also agree that the M9 will be the production digital M for some time - I would guess another 5 years. Of course, the value of a used M9 will also depend on whether Leica can (or will) offer digital hardware upgrades to convert it into an M9.2 in the same way that material upgrades were offered to convert an M8 into an M8.2. This is a whole other question, but it will be crucial to how used M9s are priced.
