That would be my understanding.

The word 'authorization' is from the 1.0 (a) version, and meant to grandfather in other OGL versions. Wizards is trying to use that as a 'kill switch' on it. You might argue that they can revoke the 1.0 (a). That would only mean that no new 5E OGL instances would be valid, because WotC is no longer on board. Wizards is announcing that it wants out, but I don't see any mechanism for 'deauthorization' at all in the OGL 1.0.

I think future development of 5E material becomes a grey zone and this casts a shadow over continued publishing of existing products for people who sign on to OGL 1.1. You might be signing onto wizard's version as part and parcel of what you sign-- so be damn sure that you're not signing away your 1.0/1.0 a rights when you bargain with WotC.

Everyone else can not sign and tell WotC to pound sand.