My buddy "restored" his grandpa's Jeep CJ5 with a brand new tub that came from the Philippines. IIRC it was only like $2500 (looks like they are $3500+ now) and there were some weird quirks compared to the original but I was pretty impressed with it. His original one was maybe fixable but had a LOT of rust. I think if you are OK with making adjustments and modifications to make things fit, it's a really great concept. I just doubt you'll ever see any less common stuff - probably relying on junkyard donors indefinitely for a 75 Pontiac Bonneville or a 42 DeSoto sedan.
Hopefully their processes can make really high quality fitting parts, I have never been impressed with aftermarket body panels. One fender on my F150 was sort of too short... the front valance on my stepside truck has wrinkles around the turn signal light holes, a Ranger hood from Taiwan was really floppy and flimsy...etc... fit & finish is always lacking.