How much is your music worth to you? At what point would you stop making music if you weren't being paid enough?
How much are you willing to pay for access to people's music?
These are some fundamental business model type questions that will end up determining if the system can sustain itself. If people are only willing to pay $1 per month, and artists require that users pay $10 per month, then the system is not sustainable. But if users are willing to pay $5 per month, and the artists can be supported for $5 per month, then all is well.
Before this exercise is over we'll have to do some math. Subscribers times fee minus overhead divided by tier 2 artists = success or failure.