I don't know if everything associated with Karl is totally dead, he seems to have have a fairly solid core of followers (not that they have the ability to purchase/support any such project, but I digress), and his while his channel has shrunk recently it seems to still be fairly solid.
He's definitely alienated a large portion of the 2A community, and that's never going to change now. "Big" projects like the WWSD rifles and any collaborations with other 2A tubers are absolutely not happening. Apart from Russell (who, if he's smart will start distancing himself from Karl) and Troontical GF, I don't know of anyone who would have anything to do with Karl now, and that kind of project/content will have a far more limited audience than anything he's done before.