I tend to agree with some of the posters above in that I don't see many, if any, new 35mm or MF cameras being developed from here on out. I claim no particular expertise or knowledge, but I'd wager that large format photography stands to benefit most from 3D printing because it's a lot easier to design and build a large format camera. You don't need a shutter, film advance mechanism, light meter, flash, or any complex mechanicals; you just need a light-tight box that can hold a lens and shutter (or a pinhole) and mount a film holder.
The upshot for me is that I can finally afford to own a camera that I can use to make images I could only dream about before. I've got a phone for the happy snaps, but to be able to shoot large format after all these years? That's amazing.
EDIT: I think a point that I left out is that 3D printing also means you don't have to stock cameras, parts, pay for shipping, or anything like that. Just download the files and in x number of hours, you can print the parts you need to build a camera. For the kind of volume that these cameras seem to sell in, this is a great match.