I'm also a previous Crossover customer who now uses proton (via lutris). I have to wonder if something like Crossover necessarily needs to exist in the long term; I suspect that part of the rationale for it was that they needed some sort of UI to present/sell the real work they did to make stuff run smoothly without needing users to do a bunch of manual Wine configuration. Obviously there are business caveats to tying yourself so closely to only one paying customer, but it doesn't seem like there's much of a technical need for the work they do to be tied to an in-house UI.