I don't know how big the market is, but there are definitely musicians out there who would love to be able to buy clones of a wide variety of out-of-production

I don't know how big the market is, but there are definitely musicians out there who would love to be able to buy clones of a wide variety of out-of-production analogue ICs to restore vintage equipment, build kits that depend on those parts, and so on. VCFs, VCOs, etc.