Sooner or later, open source digital textbooks will drive profits out of this business, much as Wikipedia (for all its warts) killed the encyclopedia business, digital or otherwise. The current system is corrupt, expensive and parasitic. It won't be replaced overnight, but there are moves afoot, for example here in California:
In the meantime, the mere existence of cheap digital technology makes high-priced textbooks a target for illegal replication, even if they are not in digital form to begin with.
So I don't see a very bright future for traditional educational publishers.