"De-authorise" doesn't mean anything in the abstract, and I would be very surprised if that phrase appears in v 1.1. (It is not part of the leak that I saw:
We got an official leak of One D&D OGL 1.1! Watch Our Discussion And Reactions!).
If v 1.1 describes v 1.0/1.0a as not an authorised licence agreement, that will have meaning only in the context of the rest of the contract, which will explain the significance of a licence being authorised or not authorised.
Trying to guess what terms WotC will actually insist on is commercial speculation, not legal speculation. From the legal point of view, they could do what you suggest, or they could make it a requirement of entering into the new licence that a party cease to distribue any work licensed under the current OGL. I don't see that either would pose any legal problem.
Here is the whole problem with the idea of WotC having any power to 'de-authorize' earlier versions of the OGL. I enter into the OGL 1.0a agreement between myself and "the Contributors" (section 4), which is defined as everyone who ever put content under the OGL (section 2). Furthermore I UNILATERALLY have the option to decide which version 1.0, 1.0a, 1.1, etc. of 'authorized' (by WotC presumably) version of the OGL (IE its a genuine OGL, they get to make that determination, but they cannot 'unmake' it) I am receiving/giving my rights under. 1.0 and 1.0a do not speak of any power of WotC to rescind the license, and once other Contributors begin distributing the OGC under either of those licenses, they -literally as a fact- cannot 'undistribute' it anymore.
I can simply, at any time now, claim my rights, by abiding by OGL 1.0(a), to distribute that content, and as a fact I have said content, because it has long since been distributed to me by other Contributors as part of their exercise of the same rights. That's it, as long as I don't choose to use 1.1 and whatever 'deauthorize logic' is in it, that license doesn't exist in reference to my rights and obligations. I never have to even read it, or be aware of it. WotC can say THEY now choose to use it, but the cat is already out of the bag! This is EXACTLY HOW PETER ADKINSON INTERPRETED IT. In his and Ryan Dancy's own words, repeated many many times in many places this is the interpretation intended by the authors of the license, and the interpretation that was accepted by the other Contributors, plain and simple. The license is intended to be, and is stated to be, 'perpetual'. Its rights and obligations exist 'in perpetuity', which is a time period without end. Only failure to abide by the terms, or the finding of the whole license as legally invalid, would end them (and only WRT the specific parties and/or jurisdictions).
Furthermore, even if WotC actually believes that the OGL can be 'revoked' and existing license holders severed from it, what stops these holders from asserting either laches (WotC 'slept on its rights' and thus harmed them by not asserting this 20 years ago), or that WotC is estopped from even making a claim in court that the license asserts such a right, because they have asserted otherwise for 20 years (these types of assertions are complex and somewhat overlapping in fact). OGL is also a bad license in that it talks about the copyright of the LICENSE, but it never clearly discusses the copyright of the MATERIAL THAT IS LICENSED. So there may be issues of what is called 'waiver' involved. Normally a good contract/license (see the CC Org licenses) includes a 'non-waiver clause' which specifically states that the copyright, and all other rights, to the licensed material remain with the original holder. OGL doesn't specifically do that, which is OK in a general sense, but weakens the overall force of the thing and might cause some doubt as to exactly what the terms actually are.
This is all just more of the general argument, do not use the OGL! Even the 1.0a OGL is a BAD LICENSE. It wasn't well written to start with, and aside issues of WotC being privileged, stands a much lesser chance of actually working correctly than a CC license.