Let us be clear : I MADE NO SUCH ASSERTION. I do not understand where you got the idea that I did.
In fact, I asserted that WotC cannot withdraw their offer of a contract (admittedly, I used flowery language, my apologies). The Carlill case you are citing works against you, because it is an example of an offer that could not be withdrawn!
There is no mechanism for doing that. Indeed, the Carlill case you site is one in which the company could not retract an offer they'd made - so clearly you know this is possible.
Please educate me. What in Carlill is evidence that WotC can withdraw its offer? Because, as it stands, the case isn an example of the opposite.
That's generally true. But one can construct exceptions, and the stated intent in this instance was to do precisely that.
"I also had the goal that the release of the SRD would ensure that D&D in a format that I felt was true to its legacy could never be removed from the market by capricious decisions by its owners." - Ryan Dancey, Nov 23, 2010.
There is no mechanism for doing so, because the offer and acceptance terms are contained within the license itself, which explicitly cannot be modified. Thus, once extended, the offer cannot be withdrawn. As above, this was intentional.
Again, the license contains its own offer and acceptance terms, and explicitly contains language that it may not be modified. In addition, there is no physical way for WotC to modify it - they cannot reach into other people's documents and alter them to remove the offer from the license.
Make no mistake, releasing things under the OGL is risky precisely because the licensor can't stop it once they've done so. The OGL is in many ways just a step or so off from just making the thing public domain.
Again - In Carlill, it was found that the offer was binding and enforceable, and the company could not withdraw. So, I fail to see how that argues against my point. Carlill establishes that unilateral, open ended offers are a thing.