Bingo! But there is still money to be made here.
Bundle a high quality open source textbook with tons of extra examples, auto-graded quizzes/assignments when possible, cheater detection, etc.
Provide regular updates so that Google doesn't know the answers to all the homework assignments/quizzes. Scrape the answers that are provided by google and incorporate them into the cheater detection.
Also provide a bit of analytics on top of the quiz/homework infrastructure. Or at least provide robust excel export so that instructors can figure out if there are clusters of students struggling with this or that concept.
And then sell the bundle and give some kick-back to the author(s) of the open source text (because it's the right thing to do, but also because the authors are thought leaders and will plug your product if they feel you're providing a valuable product at a reasonable price without screwing anyone).
Trying to write better textbooks than seasoned and altruistic professors is a losing battle.