Ran across a fascinating post by Robin Sullivan at
dealing with the changes in epublishing. Sullivan (whose husband is Michael J. Sullivan, a fantasy author) keeps records of her husband's sales and also tracks the Writers Cafe forum on the Kindle Boards. And she documented the change.
Basically it happened a lot faster and more sharply than I thought. According to Sullivan, the change started with an increase in sales in November-December in 2010 and accelerated from there. Michael Sullivan, for example, went from sales of about $1,500 a month for the self-published and ebook versions of his novels to making just over $100,000 in the first five months in 2011. Almost all the increase came in ebooks.
In her blog post Sullivan then analyzes the reports from Writer's Cafe. Of the authors reporting, the number of writers selling more than 800 copies a month of their books went from about 30 a month to around 80 a month in the same period. By the end of the period, the top ten writers were making between $3900 a month and $16,000 a month from their ebooks.
To which I can only say: "Write on dudes and dudettes!"