Rhapsody doesn't have "another" 30% to give. Their margins are probably something like 5%. Crapple is demanding 30% of the sale price, which leaves Rhapsody with a 25% loss.
Since that is economically infeasible, Apple is effectively mandating that they are the only ones who can sell content on their platform.
If this stands, the labels are probably going to have to give up on subscription services as a category, or lower their wholesale prices dramatically.