I think the film cameras that people find most desirable also double as nice display objects. I have a vintage camera seller near me who I chat to, and he can sell a nice TLR the same day he gets it, whereas any all-black SLR from the 90's will languish on the shelf. I have a Toyo 45c monorail and I often contemplate buying a field camera, but I always come back to the point that I'll be paying more money for something not as good. I use mine for portraits so I am not hiking miles through the countryside anyway. It's not something you'd put in a display case though and I do think that has an impact on its value.

Throughout the history of photography, the momentum has always been towards smaller formats. Technology moves on, the quality of the smaller format becomes 'good enough' and is more widely adopted. So view cameras gave way to 120 which gave way to 35mm. Digital has been the anomaly where in the initial history of the medium, format size grew instead of shrank. I suspect though that we are at the point where the historical trend resumes, and larger sensors increasingly become expensive niche products.

Plus ça change, plus c'est la même chose.