Legends & Lore blog continues to be the place for breaking news about 5e. Only, in this case, the news is nothing will break before autumn, and nothing will actually be happening until 2015 sometime.
The official reason given is quality control; they want folks to have the DMG in hand and time “to absorb the rules and how they all interact.” That seems a bit odd to me, considering the open beta testing period and online discussions about the rules organized by Mearls & Co.
So, being the suspicious git that I am, I suspect that WotC really doesn't know what they want from an OGL at this point. On the one hand, everyone expects them to have something, and they may actually feel they could benefit from one. On the other hand, they want to take the time to do it right because doing it wrong last time allowed the worst thing possible to happen: Paizo's Pathfinder RPG.
WotC's fumbling about with an OGL for 4th edition is entirely responsible for the creation of the Pathfinder game. They should have been bending over backwards to get Paizo on-board with 4e. Instead, WotC left them dangling in the wind and forced them to remain with the 3.x OGL. It could have been, and should have been, handled differently.
So the big question is, does WotC understand this? It'd be easy enough to blame the whole situation on the mere existence of the 3.x OGL. After all, without that, Paizo wouldn't have been able to scoop up all those players who didn't want to migrate to 4e.
I think that's missing the point, however. After all, nobody's talking about True20, or Hackmaster, or Dungeon Crawl Classics, or Castles & Crusades, or even all of them combined threatening D&D's dominance of the market. The real threat is Paizo. And that's because Paizo has something that WotC lacks: an effective marketing juggernaut.
People know about Pathfinder, people are excited about Pathfinder, people love showing off their Pathfinder stuff. Pathfinder is bright and shiny. Paizo is seen as friendly and excited about gaming and eager to promote new talent and neat ideas. Paizo oozes cool; people may doubt whether or not they'll like Paizo's next adventure path, or think that Golarion is too generic or mish-mashy, or worry they're putting out too many hardcover rulebooks, but nobody doubts that the next things coming from Paizo will resonate. They will look cool, they will feel cool, and lots of people will be interested in reading them.
And that's what WotC needs to worry about. They should fear looking like also-rans, which is why the discussion of their covers does matter. They wallowed for six years in the New Coke debacle that was 4e marketing and trade dress.
5e is a chance for WotC to start over with D&D and it certainly looks like they're taking. A strong and focused OGL would be another potent arrow in their quiver, so I can absolutely understand them taking their time in crafting one.