Something that would mitigate my answer would be whether drawings were available for the parts. The early kits (-3, -4, possibly -6) had actual plans. The plane could be built from parts that the builder fabricated off the drawings in the plans set (actually done, in a few cases). Newer kits, not so much. Not at all, actually.
Yeah, I can get a part for a '34 Ford, but there were hundreds of thousands produced, and a still-strong market to induce independent production of parts. Total count of all RVs flying, around 10K, according to Van's and a recent thread.
With emerging computer aided manufacturing and high quality processes getting cheap enough for very small shops and short runs, we could see independent sourcing of parts, but production drawings from the original mfgr would make that a lot more likely.
No vote cast, because I don't really get a vote (no stock in the company).