My guess is that it will cover all WotC material. That is, it will serve as a license to quote a certain range of WotC products, most specifically, all the "core" products. So one can always republish a creature or add standard wording for an ability. It will advise HOW to build elements in the system, such as classes, creatures and weapons. It will focus more on the guided creation of material than on the material itself.
I really don't know what it will be. I don't even know how we will post it. I don't even know how the Wiki will be able to handle this new beast. Of concern is that even established publishers are scratching their heads over the new state of affairs.