Lots of questions were raised by WOTC's vague promise of a "program" for third-party D&D publishers. Will there be something like 3e's open-source-style OGL license? Something like 4e's limited and revocable GSL? An "app store" model where products must be approved by WOTC?
To me, one key piece of evidence suggests that pretty much everything in the free "Basic D&D" PDF will be open content, making Basic D&D the 5e equivalent of the d20 SRD.
A preamble first: The d20 OGL license pretty much gave away the store. Most of the PHB is in there, apart from character creation, leveling, and a handful of iconic and original D&D monsters: beholder, gauth, carrion crawler, displacer beast, githyanki, githzerai, kuo-toa, mind flayer, slaad, umber hulk, and yuan-ti. There's really no point in 5e trying to protect any OGL monsters, since they're already basically free content. But WOTC probably doesn't want to give away anything ELSE to Pathfinder and other competitors. So if there's ever a 5e OGL-type open license, we'd expect it to exclude the beholder, gauth, carrion crawler, etc.
OK, here's my evidence for Basic being released under an open license. In last week's live Q&A, Mike Mearls listed a bunch of the "iconic monsters" in the Basic PDF. He read a pretty big list: chimera, centaurs, orcs, ghosts, giants, mages, acolytes, warriors, mummies, ogres, skeletons, ochre jellies, dragons, giant spiders. Notice anything missing? How about any monsters from D&D's non-OGL list: beholder, gauth, carrion crawler, displacer beast, githyanki, githzerai, kuo-toa, mind flayer, slaad, umber hulk, and yuan-ti?
Apart from dragons, the beholder is arguably D&D's most iconic monster - it's the 5e Monster Manual monster - so its absence from Basic's list of "iconic D&D monsters" is striking. Its absence really makes sense only if everything in Basic has to be open content.
I don't necessarily think that 5e will use the OGL itself. There might be more carefully-worded protections against competitors. But I do think that the license will be free; it won't require WOTC approval like the 4e GSL; and it won't be arbitrarily revokable without cause like the GSL.
There's one problem with my theory. I doubt the 5e license will be MORE permissive than the OGL. We know that Basic will include character creation information, and character creation and leveling hasn't been released under any previous license.
I bet that character creation/leveling details will included in Basic but be specifically excluded from the license. That would be pretty easy to do. For instance, in the 4e Player's Handbook, the character creation info and leveling details are all in Chapter 2, "Making Characters." The 5e Basic equivalent of the "Making Characters" chapter might be specifically excluded from the new license. Everything else in Basic will, I predict, be fair game for use by third party publishers.
How sure am I in my hunch? Sure enough that I'm going to prepare my next D&D publishing project for 5e.