I found 5 Observations on the Evolution of Author Business Models by Jane Friedman via Morning Coffee – 28 October 2015 by Nate Hoffelder, which is an enjoyable site in and of itself. The author, Jane Friedman, has just returned from an Novelists, Inc. (NINC) convention / conference. I believe this event was specified as a conference, which is a convention without the booze and attendant moral indiscretions.
I'm told that NINC is an organization for authors. To qualify for membership you must publish two novels, each over 50,000 words, which seems very reasonable. Anthologies and the like don't count. Moreover, most of the members are women. So, you see, I suspect that if you're a white male over 40, you need not apply. If your a Caucasian, corpulent, beautiless, conservative gun-owning Christian, you may report for sensitivity training and political reeducation. We'll see what happens after I publish my second novel and apply for membership.
In the meantime Jane Friedman is well worth reading, and her post includes a few very helpful links. What I got out of the article is that outside of Amazon, who else is there in the digital publishing industry - and the answer amounts to a few. I published on Smashwords and later pulled my work when PayPal announced brand new rules about money transfers, holding on to funds and other shenanigans that amounted to the same old thing: We at PayPal are a large, multi-billion dollar company, we have your money and we'd like to keep it as long as possible. Besides, Smashwords was a royal pain to format my work for, and it didn't sell over there.
The other thing I learned, or rather was self-justified in re-learning, is that you have to have coffee in the coffee cup before you can see how hot it is. Meaning, spend your time writing instead of reading and talking about writing, and you'll be better off. I'm reminded of an oft-repeated proverb from notable self-made millionaire Richard Kurtz, "Take care of the gross and the rest of the problems will take care of themselves."