I may be wrong, but I don't think Canonical has the engineering resources to pull it off. Even if they did, the main issue is that Microsoft does not publish their API spec which is why Wine and ReactOS devs bend over backwards to be compatible with Windows binaries. It also does not make sense from a business perspective. Considering there is no demand for such a system outside of the very, very small number of hobbyists who run Windows games and software on Wine.