One thing I find amusing is that the article talks about the beauty of the OGL, but then in the next section talks about how WOTC now has a strong competitor in Paizo.
Funny thing is that Paizo is one of the companies that isn't directly attributable to the OGL. They came into being because WotC decided they were going to cancel the mags. It is likely, but not certain, that they wouldn't exist without the OGL - it's just barely possible that we'd still have a Pathfinder without it, albeit a very different one.
But without the OGL, we wouldn't have Mongoose, or Green Ronin, or Malhavoc, or Necromancer/Frog God. Which means no Conan, or Babylon 5 RPG, or Dragon Age, or Mutants & Masterminds, or WFRP 2e (and, thus, no 3e or Dark Heresy/Rogue Trader/Deathwatch), or...
Hell, there would be no EN Publishing, and quite likely no EN World.
All the supplements and games that those companies produced created massive excitement for 3e. Without them, 3e would not have been the massive success that it actually was.
So, there would probably be no 4e. It's likely that Hasbro would have cancelled D&D long since.
But, even if it survived, D&D would be very different. With no OGL companies to provide a way in, and with the magazines cancelled in 2003 (no Paizo, remember), there's no obvious route for people to get into the industry. Oops.
In particular, Mearls came to prominence due to his work for OGL companies (notably Mongoose, then Malhavoc, and
then WotC). Remove his contributions, and 4e looks very different from what we have. And, since he's now effectively running the whole show...
It is easy to see the OGL as an error, and think that D&D would be better off without. But that is an easy
mistake to make.