Architect of the original Open Gaming License, former VP of Wizard of the Coast, Ryan Dancey:

Yeah my public opinion is that Hasbro does not have the power to deauthorize a version of the OGL. If that had been a power that we wanted to reserve for Hasbro, we would have enumerated it in the license. I am on record numerous places in email and blogs and interviews saying that the license could never be revoked.

(source)