Oreilly author here. FWIW a ton of us were caught off guard by this as well. At the same time, I can't say I'm surprised.
My commercial incentives for working with oreilly wasn't about the book per se. I found a ton of value in working with them for their peripheral activities including safari, their strata , and AI conferences. I think other folks who write for oreilly tend to do these same things.
Pointing out where oreilly is making money: It tends to be large companies paying for access to safari now.
They will be putting other content in there now.
Print is a dying media. That being said: A ton of people prefer print still.
I don't think any end user or author of their's is "happy" about this per se. 1 benefit I liked of the online store was the ability to point people at that for pre releases and updates. You can't really do that with amazon.
I may be naively hopeful in saying this, but..
That being said: this should allow them to invest in other distribution channels now as well.
Oreilly showed they know how to run a distribution channel and may use that expertise in other areas.
As someone closer to this than a lot of people, I'm happy to answer general questions about the process, other ways this could affect us etc, if that helps.