That is what I had thought, and was referring to. They can revoke their offer to license.
Yes. But this has no real effect, because existing contractual parties retain the right and obligation to sub-licence WoTC OGC (along with everyone else's OGC).
WoTC's legal argument appears to hinge on Section 9 and the word 'authorised'. But their argument appears to be so weak, that I can't think of how to set it as a Contract problem question for my PG Law students - and I've been trying! The words that come to my mind are stuff like 'laughable' and 'ridiculous'. Now I'm sure their lawyers could put together some kind of an argument to present in court. But it seems incredibly easy for the other side to shoot holes in it. This seems more like a threat intended to terrorise the 3PP community, not something intended ever to see the light of a courtroom.
Edit: And Lisa Stevens/Paizo are clearly aware of this. And Lisa at least has the deep pockets to defend and almost certainly win any action brought by WoTC on this.