I read the introduction to that article. The second sentence after n 30 is
The role played by contract in the realm of license is a different one - it provides a means for licensors to protect a licensee's interest in non-revocation without granting an ownership interest in the property.
That seems to me a fair description of what most people have understood the OGL to involve. A few sentences on, the author says
There is no reason, in principle, why copyright law, like land law, should not permit the creation of irrevocable and exclusive license interests by means of either property conveyance or contract, leaving each to be enforced through the appropriate means. A clear recognition that copyright owners are able to create irrevocable, nonexclusive licenses by unilateral deed would be particularly helpful to owners who wish to grant open-source or Creative Commons licenses.
I don't think this contradicts the idea that the rights and powers granted under the OGL may be irrevocable, even if WotC were to rescind/revoke its (hitherto) standing offer to license to all comers.
This characterises the nature of a licence as a non-proprietary interest. Which I think everyone understands and agrees with.
But surely it is possible, by way of contract, to bind oneself not to exercise the power of revocation? What the remedy would then be for purported revocation - a voiding of the purported revocation, or damages for the consequences that flow from it - I don't know, as far as US contract law is concerned.
Well, I think the passages from the Iowa LR article provide support.
Of the cases you linked to, the only one I looked at is the Mueller one - which concerns oral licences giving a right of way to neighbours, and is primarily concerned with whether or not they can give rise to an easement by way of long user. It doesn't seem to me to have much bearing on whether or not a contract with the intricate written terms of the OGL can bind the parties not to revoke. The Court, at 33, even allows that "the agreement that the mutual use was to continue "as long as both houses stood" might give rise to a claim that defendants' revocation at this time operates as a fraud upon the plaintiffs" - but puts that matter to one side, as even so that would not establish the easement the plaintiff sought to claim.
I'm not saying that you are definitely wrong, but I'm not seeing how the two sources you point to that I've reviewed support the claim you're making. (It's late at night where I am, so I'm not going to check the other sources. Do they bear more directly on the issue at hand?)