I don't agree with your second paragraph, when you say "it's largely going to be an issue of . . .".
As I said in my post, I think the most obvious argument that it is not a version is that it does not permit licensees to sub-license the rights that the OGL v 1.0/1.0a requires them to. An instrument that generates obligations at odds with those of another instrument doesn't seem to me to count as a version of that other instrument.
I think that you are treating the current OGL (v 1.0/1.0a) as if it were a statute. It's not. It's a private legal agreement. WotC is not bound, in respect of its future offers, by the terms of its old offers - except with respect to people who took up those old offers, and hence entered into a contractual relationship with WotC. The fact that WotC has promised Paizo that Paizo can use the 3.5 SRD under any future version of the OGL doesn't mean that, if WotC now licenses its 5.5 SRD to you under the OGL 1.1, that WotC is obliged to also let you use the 5.5 SRD under the terms of the OGL 1.0. (Unless the OGL 1.1 says so. Presumably it won't.)
How do you think WotC is coming under the obligation that you say it is under, in relation to future offerees/licensees?