I disagree; I don't think it is at all unrealistic. I thought I had made my reasons clear in my original post, and I hope this post will not belabor the point.
By removing the film transport requirements, you remove much of the mechanics of the camera - mechanics is the expensive part. That leaves the shutter and mirror mechanism as the only complicated mechanics, and the mirror mechanism does not have the tight timing requirements of the shutter. It just has to get out of the way before ths shutter opens. That leaves the body, with lens mount system, the prism, the sensor and memory, and the light meter.
The sensor, memory, and your RGB light meter are electronics. The major cost of electronice is developemnt costs and setting up the production line. Since the meter is the same as the F-5, those costs have been long amortized. Memory chips are cheap even now and not likely to increase. That leaves the sensor, which is new and should drop in price over time as most electronice do.
The body can be an investment casting and that is overkill. Investment castings are not terribly expensive. Since the body no longer houses the precise mechanics of the film transport, internal machining tolerances are reduced, with the exception of areas that house the sensor, shutter mechanism, and prism. The rest of the body is simply a compartment for memory, batteries, LCD, and some switches. The only part of the body that has to be light tight is the area that houses the sensor-lightmeter-lens complex since there is no film.
The lens mount will require the same careful machining it does today, but I am sure the lines are CNC today; that reduces costs.
The pentaprism costs remain, as does the cost of the AF motor; the AF sensors are electronic.
As for viewfinder shutter, how much can that cost. All it has to do is be reasonably light tight and close at the push of a button; no real precision timing required; it can probably be stamped out. The vertical grip - nothing more than a battery compartment with a couple of switches and contacts. It's probably way over priced today for the F-100, but that's what you get when you have a sole supplier.
You may be correct, that the sub-$1000 DSLR will be an N-65 equivalent, but it will be a marketing decision that makes it so not engineering or manufacturing constraints. The one hope is that since digital cameras are mostly electronic, and much of that electronics procured from third parties, the entry costs for others to enter the field will be reduced, which will engender competition and force prices down.