That is so blockchain: a solution that does not work and users do not need. Blockchain only sees hashes, so it has no way of knowing if that hash of a new song

That is so blockchain: a solution that does not work and users do not need. Blockchain only sees hashes, so it has no way of knowing if that hash of a new song that was just uploaded is really a remix. But, if you solve this somehow (and I bet you can't in a way that can't be gamed), people can just distribute remixes outside of blockchain altogether. No blockchain is going to help you collect royalties from youtube stream. Second, "money distribution for remixes without trusted parties" is not a very common problem. If contract participants want to cheat each other, they can do it easily by lying about number of listeners, they don't need to do something trivially detectable like messing with contract itself.