I had already been contemplating this, because unity has specifically added functionality that allows for things like this. However, I'm not super-confident in how good their functionality on that is, and it seems to be fullscreen-only as a feature. I'm also not sure it works on all OSes.
It's not something I want to even attempt for v1.0 because it's such a risky thing, but it is something that is increasingly feasible as the engine has evolved. In terms of the coding, there would be some needed splitting done, for sure.
Right now in the "for later" list.