It really depends on much more locked down the engine will become with ES6. Fallout 4 was notoriously hard to mod for and the modding community suffered for it.

It really depends on much more locked down the engine will become with ES6. Fallout 4 was notoriously hard to mod for and the modding community suffered for it. Of course modding difficulty doesn't translate directly to how well Proton will run it, but I fear it will make it difficult for it to be optimized.