The cost of any widely available item will trend towards its marginal cost. A non-rivalrous good with zero marginal cost will therefore trend towards a price of zero. Digital copies of things fall under this category. Therefore, you cannot expect to be able to make money by having a profit margin on each item sold on these types of products. You cannot make money this way.
You may lament this fact, but it is the reality. You will have to make money some other way. There will probably never arise a perfect substitute. The worst case scenario is that the modern but pre-digital age was a golden age for production of these kinds of now-digitizeable things, just as ancient Egypt was a golden age for the production of pyramids.
But you can’t put the genie back in the bottle, and you can’t complain that there isn’t any substitute business model to cover your situation. Reality is what it is.
① http://www.cracked.com/blog/6-harsh-truths-that-will-make-yo...