I had another Aha! moment this morning answering emails. One of the most common things I see in my In Box is the statement "I'll eventually get an FX body." This usually comes in conjunction with the "all I can afford now is DX" and "but lens choices are problematic" statements. People worry that by buying DX now they're committed lens suicide, as they won't have the right stuff when they move to FX.
First, even if you buy a DX lens today, it's not as if its value plummets to zero tomorrow. We've got almost 9 million DX users already, and that number is growing. Just as Nikon lenses have always retained some value over time, I think DX lenses will do the same. So consider that you'll lose 20-40% of the value of the lens as a rental charge.
But that wasn't my Aha! moment. While I've long told people that I didn't think photographing with FX in the future was inevitable--sensor pricing means DX will always be more affordable than FX--what I realized this morning is that quite a few pros I know have downsized from what they were using with film and are perfectly happy. I know 4x5 and 8x10 film photographers who now use MF digital. I know MF film photographers who now use FX. And I know plenty of 35mm film photographers who now happily use DX.
Digital downsized us all. In retrospect, it's easy enough to see why. ISO 800 was acceptable with 35mm film, but more than acceptable with DX digital, for example. At the high end where "size matters," to get the best quality prints most folk had moved to using digital scanning. While you can scan large format film quite high in terms of pixel count, above a certain point you mostly start resolving grain (which does hold some additional information, but which is difficult-if-not-impossible to make into grainless information). Moreover, the cost of scans starts running very high, so you per-image costs run extremely high. Thus, very high pixel count MF backs started to become appealing to the LF film crowd at some point.
I'd say there's a built-in bias towards smaller, not larger, at least if the image quality doesn't suffer much. My mentor used to get asked a lot about why he didn't use MF film. His answer was simple: because I can't get MF equipment into the places where I take images (he was an adventurer and climber). Most of us have a built-in bias for smaller. Large format film landscape photographers, for instance, were notorious for taking one photo a day, and never very far from their vehicle, as the equipment was too big and bulky. I'm sure someone must have done it, but I don't know anyone personally who took an 8x10 film camera to the Wave (a famous scenic point in the US that's accessible only on foot over tough terrain). But I know MF digital photographers who have.
No, I don't think we're all going to be using FX bodies in the future. I'll bet we all end up at least one size smaller than we were with film, maybe more.