Android/Chrome Hybrid Device
Picture a 10" tablet with a Windows 8 implementation of Chrome OS being the desktop and Android being the Metro interface. Ideally the hardware would be in a Surface Pro form factor to best use both environments.
You get the full web, with all the extensions and apps from the WebStore along with access to the PlayStore - the best of both worlds. This has to be a Nexus device or something Moto otherwise it would not be very successful.
It would cannibalize the sales of both Chromebooks and 10" tablets and yeah it would be a Google's clone of Windows 8 and Surface but it would make 10" Android tablets and Chrome OS more mainstream productive machines.
I am sure inside Google Labs, they already have a prototype of this at a fraction of the cost of a Surface Pro, just incase Windows hybrids catches on.