You should just run benchmarks on a wide range of computer configurations. In the current state of things, your game will still render virtually at 1080p on lower resolutions. Shaders could also cause big caveats, as they will treat pixels on screen. You can always have parameters to deactivate those though.
And be wary of the kind of computers your target audience have. Casual gamers are more likely to have slower computers for example.
In all honesty, after a couple of months working on c2 with an engineer specialized in web technologies, I wouldn't go anymore for complex games with dense visuals. At least until more users get better hardware and/or the engine proposes several more rendering optimizations (like rendering the game at a lower resolution/some mip mapping system ?, and rendering shaders at the game resolution, if these can be implemented in a sprite engine).