Storing Music in Blockchain is not possible because each block contains only 2 mb data and music needs 4+ mb datas to store. It can be that music industry can do transaction in cryptocurrency but they cannot store music in blockchain.
We have to see option on erc20 tokens if it is possible, it it got success then it will really give a very big boost to erc20 token platform.
You're right with what you said but music wont be store on the blockchain because blockchain will only be use to monitor/calculate the number listener or download of music. However, I have seen alot of music project which were implemented on the ERC20 and I believe it work fine cause if not there wont have be more.