The following theme mock-up by ~RustedThorn may be a tad indulgent on the branding scales, and closing an application via a menu every time would get real annoying real fast, but you know what? I really don’t care. It looks beautiful.

ubuntu_theme_mockup_v3_by_rustedthorn-d36ve27

Check out the full image @ rustedthorn.deviantart.com

Idea mockups