The more I read from attorneys, here and on other sites, the less certain about that I become. Because as I understand it, here's what has to happen for a court battle to take place:
1) WotC goes ahead and officially declared the OGL v1.0a to be revoked/de-authorized as of a specific date.
2) Some publisher declares "damn the torpedoes!" and keeps publishing new content under it.
3) WotC sends them a cease and desist letter. [Optional]
4) The publisher files for
declaratory judgment. [Optional]
5) WotC files suit against the publisher for copyright infringement.
6) The publisher counters, saying that they're not infringing on WotC's copyright because they're publishing under the OGL v1.0a.
7) WotC points out that they de-authorized/revoked the OGL v1.0a, so the license is invalid, and thus the publisher's stuff infringes their copyrights.
8) Either a judge or a jury decides who's right.
9) Appeals are filed; if accepted, go back to step 5 and repeat.
Now, steps three and four are, as noted, optional; I'm given to understand that the whole "declaratory judgment" thing is basically a step that doesn't legally force anyone to do anything.
What's more notable is how unlikely steps 2 and 5 are; most publishers aren't going to want to operate in an environment where they're essentially courting a lawsuit with a multinational corporation, while Hasbro doesn't seem to care nearly as much about a tiny publisher (and compared to them, all other TTRPG publishers are tiny) doing their own thing; they're in it for the VTT subscriptions/micro-transactions.
So we might not get the court battle that a lot of people are expecting.