If they use a system like that of Music then they could be integrated on the same blockchain. I believe cob explained the need for a separate blockchain somewhere but I don't have any references for it, you could look through his posts.
There is no need
for a separate blockchain. Any BitShares Music features could be implemented on the BTS blockchain. But that would require another "merger" and diluting BTS even more to absorb Note holders and the right to use all BTC collected in the crowdsale. I don't think anyone wants to go through that again.
I agree with keeping BitShares Music as a separate DAC with their own stakeholders. And I agree with BitShares Music having its own asset that is pegged to the US dollar since a price stable currency will be essential for the users of the system.
If these requirements are satisfied in the typical way, this necessitates NoteUSD collateralized by Notes on a decentralized exchange on the BitShares Music blockchain. Of course there is the other way
of doing it that has its own trade offs.