...China currently has equipment brands like TTArtisan and 7Artisans making M mount lenses. That is why I am thinking the next step for these companies could be a body.
I don't think either of these companies
makes lenses... they
design and
market lenses, which are made by various original equipment manufacturers (OEMS) such as DJ Optical of Shenzhen, which is explicitly credited on 7Artisans lenses. And even though DJ Optical is coordinating the manufacturing process, the metal and glass parts most likely are produced by various subcontractors, and assembly may be by yet another subcontractor. It's the same way lots of other small-to-medium-volume tech products get made -- agreements are signed, CAD files get emailed back and forth, subassemblies get shipped, and eventually Amazon delivers a box to your door without anything we'd recognize as traditional "manufacturing" having taken place.
This works with specialty lenses because, as Thom Hogan has pointed out, fabricating metal parts can be done at moderate scales without a heavy investment -- the numerically controlled lathes and mills can be making lens components today, hi-fi components tomorrow, and home medical equipment next week if that's where the orders are.
A camera body is a trickier proposition. It needs a sensor, image processing electronics and storage and display hardware and software. Most manufacturers handle this with application-specific integrated circuits (ASICs), which is what all those trade names such as EXPEED, DIGIC, etc. refer to. I've got a data sheet somewhere saying that the setup cost to manufacture a single ASIC is the range of $5 million, so this is not something a small vendor can tackle on a speculative basis. (Pixii gets around the issue by using a field-programmable gate array, or FPGA, instead of ASICs; the FPGA is basically a "blank chip" that the designer can configure as needed. This makes low-volume manufacturing feasible because you don't have to pay up front to fab a bunch of ASICs, but FPGAs are relatively expensive so the cost doesn't come down as much with higher volumes.)
Of course if the demand is there, the same thing could happen as has happened in a lot of other high-volume electronics products: Some supplier could come up with a generic board that would provide all the functions needed for a basic camera, and then would-be "manufacturers" could configure this board to use whatever sensor, LCD panel, storage, and lens mount they could get at a price they were willing to pay. If the user would be content with focusing on the LCD or EVF, there'd be no reason such a camera couldn't be made with an M-mount, a Nikon or Canon or Sony mount, an Exakta mount, or any other mount for which the vendor could discern a market. (Rectaflex, anyone?) It could be relatively cheap, too, because most of the parts could be the same regardless of mount.
But would you buy one? You'd have to assume it wouldn't perform as well as a camera with its sensor stack customized for a particular lens mount, and with image processing handled by ASICs designed for the specific sensor's characteristics.
