Assuming a hand-held design ... I would suggest that the mechanics of any newly manufactured camera would have to be quite simple. Structure must be uncomplicated..something that can be easily machined, molded or 3D printed in metal or composite plastic. Closer to a Brownie than a Nikon. Probably 35mm film, since there have already been manufacturing and supply problems with 120.
No batteries, electronics or in-camera metering. Scale focus, simple rangefinder or twin-lens reflex. If interchangeable lenses, then perhaps Leica M, adaptable to mechanically focussed Nikon etc. A fixed lens design could be proprietary. A modular construction might be nice, like the Graflex XL etc.
A simple leaf shutter would be easy, but a multi-speed leaf shutter would be hard to fabricate because of necessary special skills and tiny, hard-to-source gears and springs. Fabric focal plane perhaps, or something entirely different like the ingenious rotary shutter in the Universal Mercury cameras.
Individual units built to order or in very small batches. Retail price range? A week or two of wages for the average person... currently around $900-1800 in the USA.
With the possible exception of instant print technologies, we must accept that chemical photography in the not-so-distant future will be the pursuit of a increasingly tiny minority of photographic adventurers. The sophisticated and intricate camera designs of the 20th century film era will not be practical because consumer support is absent. As for roll film, I expect that most conventional color emulsions will soon be extinct because the complex, multi-layered coating process has so many quality-control difficulties and material inefficiencies at low production levels.
Black and white emulsions are easy to make and will be around as long as anybody is willing and able to assemble the ingredients and spread them onto something. Even in the absence of suitable plastic film, there's always glass plates or even paper.
Think of future analog photography as something akin to hunting wild game with a bow & arrow or a muzzle-loading black-powder musket ... just as much a sport as an art.
