Does Wizards of the Coast think that the d20 System is the only RPG that should be published?
Nobody at Wizards of the Coast believes that OGL/d20 will cause the market to reject all other RPGs. There will always be a market for game systems produced by publishers who are determined to forge their own path, or to push the envelope of design. And there will always be people who find different game systems more entertaining for different types of games and different genres. Over the long term, however, Wizards of the Coast hopes that the systems which are widely available in the market also become Open Games, and that instead of supporting dozens or hundreds of different games, the market chooses to support a just a handful.