Please don't think I'm not taking your question seriously, but I do think the future model is a donate button (I also say above, I think it boils down to begging). I do also consider this model sustainable since, even ignoring all the other ways fame can be monetized, the potential audience is 7 billion people and a gift of even $1 from even 0.001% is $100,000 - enough to justify most indie projects. But if that's too risky, I am encouraging people to put the horse back in front of the cart and to hit up people through kickstarter... (It still amounts to begging/patronage, but it's more predictable by being up-front.) The main difference between that and the old publisher-oriented model, is that creators have all the control over the terms.

I would also love to see people release commercial stuff more under CC-SA and similar (even if they still charge for distribution), or the FOSS licenses - assuming they need one. There's no reason they can't generate income, even while being shown through a subscription. The license doesn't change the distribution model. (Ubuntu is asking for donations. I would love to see some stats.) I think people just need to get used to flying without a net (copyright).

Take Netflix for example: they are producing their own shows. Like iTunes, all the content on Netflix can be torrented, but Netflix is easier for non-technical people. I don't even think copyright is necessary for either of Netflix's or iTunes' success. Netflix is a subscription, but I think they could make a similar amount if their shows were CC-SA licensed. People pay for both Netflix and iTunes because downloading is simply harder and more likely to give their computer an STD, even if the quality can be better ( https://news.ycombinator.com/item?id=5621119 ). Copyright still affects the food chain today, but Netflix has convinced me that they don't need copyright to keep the game going.

What's more likely however, I think, is that we will see something like the 6.4/93.6 ratio continue into the future, painfully and in spite of copyright, and with much resentment, until that hostility turns to acceptance (though, by then we'll probably have other generational gaps to deal with) - assuming we can get through the next 10-20 years without a censorship/copyright-centric police state. 6.4% of 7 billion, for something priced as low as $1, is still revenue of 448 million, even without budging that ratio, so I have no doubt creators will do well.

Edit: I don't feel like waiting 40 minutes for the reply button to appear on your comment, but I suppose only time will tell. In the mean time, the pro-copyright-ons and anti-copyright-ons will likely have to learn to live with each other, if for no other reason then so they don't collide and annihilate, sending us all back to the stone age (or industrial age).