The stockpiling concerns aren't in the "wear" parts- it's the other pieces that no other manufacturer would step-up to build. Trim, seals, knobs, handles and the like. Look at what NPW sell for Camaros and other rolling pieces of crap from Chevy- weatherstripping, chrome trim and the like. The Z doesn't have nearly the customer base that American cars do, nor the kind of aftermarket manufacturers who contribute to what used to go into a car.
Here's an Old Man Anecdote that might explain some of it for you- I was a theater projectionist for half a decade, long before digital was anything more than a future wish. I drove the film prints from San Francisco to St. Helena, CA, spliced the shipping reels on to a big reel and showed movies. Not even a platter system, although even doing "make-ups" by splicing the shipping reels into longer runs was rare enough at the time. I ran a carbon-arc lamp behind projectors that were made in the thirties, a Peerless Mag-na-Arc and Simplex E-10 projectors.
The projector drove things with a vertical gear shaft, metal pinions running in fiber gears, which wore out about every ten years or so. We dealt with Western Theatrical in SF for parts, and when we stripped a driven gear on one of the projectors, I had to go to them to get replacements. "You're lucky you're running the E-10 with that vertical drive," the parts man told me. "The E-12 went to a slanted main drive shaft, a lot quieter and easier on the parts. They never wear out. So no one's ever made parts for them. When one of those wears out, you throw it away. An E-10 you can almost build a new one out of the available replacement parts."
Don't panic. The stuff coming on to the market will make the lovely CR-Z look as hoary as the Z makes an MG Midget look. Oh, and it'll be electric and three times faster, for less money.