Henry
Autoexreginated
This is something I find very interesting. As much as I enjoyed the OGL on the customer end, I would find it hard to argue with the idea that their main competitor exists solely because of the OGL. I like that Pathfinder is around, competition is always a good thing and D&D needed it, but from the WotC perspective having such a large competitor is probably not something they were happy about; the idea that when an edition change occurs people may switch to another companies product. Very interesting. Either way I guess we benefit.
I would argue however that D&D 4e wouldn't have been any larger with or without the OGL. Instead, the 3E fanbase who weren't ready to leave it would have gone on to other games, or just shifted their creative energies to other hobbies anyway. As it is, they have a fanbase to attempt to woo back, rather than get the word out to people no longer in the hobby. Though admittedly, it makes the job of "wooing" harder.