Yes, it would be very useful to have a single OS image that could scale its user interface and capabilities to the hardware it finds attached at any given moment.
OSX already does this. Got a base model Macbook Air and a big powerful iMac or Mac Pro? Connect a thunderbolt or a firewire cable and boot in target disk mode, you'll boot from the Air's hard drive but get the full hardware capabilities of your iMac or Pro (better GPU, more CPU power, whatever).