Other storefronts... That would be nice if people could make money on those other distribution channels. Unfortunately, they can't, by and large. Most people don't find the effort worth it to even sign up with Amazon, which has a huge addressable market. I have never even seen a sales report with money from fdroid. For devs who are trying to make a living just from games, anything other than Steam, iOS, and for some people, Google Play, is basically irrelevant. Unless you land in a Humble Bundle.

As far as the loyal audience, yes, I agree with you on that, even mentioned it in the article. But that's not a living wage for most, and the latest research says that sort of environment is more susceptible to a hit-driven winner-takes-all market. That leads to an ugly place as regards the income levels for the typical dev.