I can see three scenarios. I'll note that at this point I don't think it actually matters whether OGL 1.0a is actually revocable or not - I very much doubt we'll ever actually see a ruling in court, and anyway I think the dust will have settled before it comes to that.
Most likely: WotC go ahead with OGL 2.0 in some form, and declare 1.0a de-authorized:
A relatively small, but relatively vocal, segment of the player base take great pleasure in telling WotC exactly what they think of them.
D&D continues, but the PR damage is significant. The playtest goes on, but without much enthusiasm (though, ironically, the %age of acceptance goes up - just with many fewer responses). D&D Beyond sees a small number of additional account deletions, but gains very few new accounts. However, a lot of paid subscriptions switch to free accounts. The D&D movie launches and does okay-ish (but is considered a failure by Hollywood standards) - but that's nothing to do with the OGL. The execs responsible fail upwards, either being promoted or moving to better paid jobs elsewhere.
And the 50th Anniversary year starts with a whimper - it all feels much more like a wake than a celebration.
Meanwhile, as many 3pp as can manage it shift to ORC. We lose an awful lot of the smaller 3pp, and the ones that are left are diminished. D&D's 3pp support is much-reduced, and almost entirely confined to the Guild - virtually nobody signs up to OGL 2.0.
Everyone loses from this.
Second most likely: WotC leaves OGL 1.0a exactly as-is:
The same as above, except that more of the small 3pp continue, and D&D has a bit more 3pp support using OGL.
Least likely: WotC backtracks entirely, and releases an OGL 1.0b that is more explicitly irrevocable
Most, but not all, of the damage is avoided - companies continue using the OGL, eeryone breathes a sigh of relief, and WotC is mostly forgiven. Gradually things go back to more or less where they were.
The D&D movie launches and does okay-ish (but is considered a failure by Hollywood standards) - but that's nothing to do with the OGL.
Oh, and one of the execs responsible (probably whichever is most junior) is messily fired.