My head is spinning with all this stuff. Maybe yours is too.
One thing is clear: The traditional academic book publishing paradigm (broadly defined) is cracking and will soon be crumbling. In the emerging e-paradigm there will be essentially no difference among books, courses, e-books, e-courses, web sites, blogs, and so on. With no loss of generality, then, let's just call it all "e-books," filled with text, color graphics, audio/video, animations, interactive learning tools, massive numbers of internal and external hyper-links, etc.
An interesting question is how to create (``write"?) and distribute such e-books. The amazing thing is that the answer remains unclear. Both pitfalls and opportunities abound. Here are some thoughts.
Part 1: LaTeX to pdf to the Web
Moreover, LaTeX/pdf/web has at least two extra benefits relative to a website (say). First, trivially, the pdf is instantly printable on-demand as a beautiful traditional book, which is sometimes useful. Second, and more importantly, the linear beginning-to-end layout of a "book" -- in contrast to the non-linear jumble of links that is that is a website -- is pedagogically invaluable when done well. That is, good authors put things in a precise order for a reason, and readers benefit by reading in that order.
OK, you say, but how to restrict access only to those who pay for a LaTeX/pdf/web e-book? (It's true, a pdf web post is basically impossible to copy-protect.) My present view is very simple: Just get over it and forget the chump change. Scholarly monographs and texts are labors of love; the real compensation is satisfaction from helping to advance and spread knowledge. And if that's not quite enough, rest assured that if you write a great book you'll reap handsome monetary rewards in subtle but nevertheless very real ways, even if you post it gratis.
[To be continued. Next: HTML and MathML and LaTeXtoHTML5 and MathJax and ...]