Point of order: TSR learned the hard way that you inherently limit your profits if you intend to make profit on selling books that, by their nature, appeal to only 1 out of 5 or 6 members of each D&D group. Adventures and DMG's are profit loss items, really.

What I'd love to see is the publication of lots of new setting books, either as two book sets separated into player knowledge and DM knowledge, or as one book but with a clear and explicit divider between player and DM sections like the original Arcana Unearthed did.

Modules can, and almost should in a way, be made available online either free or very cheap. Cut the cost of printing and still offer them for sale. Or POD if desired.

Much as I am loathe to say it, though, the best way to bilk money out of the gaming crowd is to print lots of books aimed at players with lots of fun new crunchy rules that they might not be required to have, but really really want.