The threat is enough. And I understand why the 3PP are doing it, but they're basically giving Wizards what they want without Wizards actually having to revoke the license.
Thing is, if it's bad for the 3PP to be forced out of the D&D ecosystem, it's bad for them to be scared out of it too. Either way, they're out. The burst of creative energy and enthusiasm is nice, but these companies aren't going to be as successful publishing fantasy heartbreakers as they were publishing for D&D. I'm still hoping for an explicitly irrevocable 1.0b.