This definitely no sustainable for either the protocol or any business that wishes to build on Counterparty. 5 XCP per asset will mean that we'll soon run out of XCP to burn for asset issuance, given we only have about 2.6 Million XCP outstanding, it will quickly become unprofitable to purchase XCP to issue assets. At this rate we will only have 529, 747.184 possible assets issued on the system when we'd like to have well more than that as there are trillions of dollars in assets yet to be digitized on Counterparty.

I wrote a proposal to change from burning XCP to BTC as the fee for asset issuance here: https://forums.counterparty.co/index.php?topic=150.new#new