I didn't see anywhere an indication that Apple wouldn't support open, non-DRM ebooks. They do now. If you want to build a publishing business making textbooks without DRM, Apple will be happy to support you. Distribute however you want. If you want to make them free on the iBookstore without DRM, Apple will likely support you.
When I went to college, the text books were a proprietary system with built in DRM.
The professors and the text publishers had deals, involving kickbacks I'm sure, and professors were known to demand that you used the current Edition (which was really no better, and often worse than the previous).
They enforced this by asking questions that involved answers that were different in different editions or that weren't covered in previous editions.
Further, all the books had physical DRM. The glue they were bound with and the cardboard the covers was made out of was designed to disintegrate over the course of a semester, even with good care. I kept my books on a shelf next to my desk in my dorm and never took them to class, and still couldn't sell them at the end of the semester because they'd fallen apart.
Once again, Apple's taking a proprietary industry that is used to charging high prices and trying to democratize it and bring prices down.
Apple did this successfully with the music industry before getting them to give up on DRM.
This is a good forward step with the textbook industry.
Plus by definition if you create software which supports new features you have lock-in.
Apple supports the ePub 2 standard. Apple is as interoperable as they can be. Its amazon that created a proprietary ebook standard. Apple's evolving the standard forward, but I've not seen anything to indicate that these aren't just ePub 3 books.