Idiomatically, "shelved ideas". Shelving can be more abstract, but generally it's not idiomatic for abstract-concepts to be "on a shelf".
Language aside, I think you're being inconsistent with that concept: there are better solutions for compensating artists than NFT's already, so it's inconsistent to say that you want active-solutions as a justification for working on an less-active-solution.
I'm replying specifically to "Would they not be able to send the same courtesy royalty if no NFTs were involved?" which absolutely there is not already a satisfying solution in place. No thanks for the language lesson
Language aside, I think you're being inconsistent with that concept: there are better solutions for compensating artists than NFT's already, so it's inconsistent to say that you want active-solutions as a justification for working on an less-active-solution.