The first Critical Role campaign originally was a Pathfinder campaign (thus Percy the Gunslinger as one of the PCs). So them using a different system is not out of the question. Matt Mercer is also a decades-long player who is constantly adding homebrewing rules, creatures, magic items, and character classes. He has co-authored sourcebooks with and without WotC, including the massive Tal'Dorei Revisited sourcebook released just months ago under the OGL, so him being involved in the creation of Critical Role: the RPG is not out of the question. And Critical Role has frequently shot special episodes playing a huge variety of independent RPGs, some OGL and some not.
Then there's their strong partnership with a tiny corporation called Amazon for their very successful animated series. Their wide range of products sold through web stores in various countries. Their sponsors (including WotC themselves). A massive Twitch following and heavily viewed YouTube channel.
And Critical Role have made a consistent point of being an ethical organization. Them collaborating with WotC on a special deal while ignoring what is happening to so many other independents who have relied on the OGL would be a terrible look, even if they were inclined to do it.
All of which is to say that this is a real threat to happen, IMO. Either they produce their own thing, or they collaborate with other independents, or they cut a deal. I think they will have a huge impact on this controversy however they weigh in, one way or the other.
