There's a general rule of interpretation that a contract licence of indefinite duration can be terminated on reasonable notice - an implied term. I don't think that applies here, due to eg the use of the word Perpetual combined with the specific termination provisions. And the general aim & wording of the licence as a statedly Open Gaming licence, parralleling Open Software licences.
Not to mention what WotC always said it meant, until a few days ago!
Not to mention what WotC always said it meant, until a few days ago!