welcome @Hansmoleman - I also have interests along these lines, but since I have no way of knowing when functional Smart Contracts will be fully implemented, or when we will be able to create new tokens on an actual multi-asset ledger, I would have the same questions as you (& we all do) about the roadmap & in the meantime am learning to develop smart contracts that will do most of the things above.
At some point after those milestones there should be a mass migration of Ethereum tokens like RARI to the Cardano blockchain. Periodically on this forum the marketing people & the Foundation announce that big Ethereum apps based on blockchain services have lined up for this, so I would keep following announcements like that.
Along with the multi-asset ledger will come a facility to migrate the Ethereum tokens directly to Cardano, so maybe Rarible will convert RARI as such & re-base their enterprise on Cardano, or support both. One motivation for blockchain app providers to do this are the massive transaction fees on Ethereum.
I think about these issues mostly from an online publishing point of view, which is a little different from collectibles but with some common elements like licensing. If none of the applications that migrate, or emerge anew, will handle the complex supply chain aspects like royalties, leasing, rentals, etc., maybe you can take a crack at developing it yourself, since the Marlowe smart contract language (“domain specific” to financial applications), is designed for “non code savvy” people to learn & use it, especially with the Blockly visual language: