No, you're right. And the Volt won't be one of a kind. GM intends to put this platform out there among other vehicles once the Volt takes off, and prices come down.
Remember, this isn't just about the "Volt". It's the
E-Flex platform. Capable of powering itself via hydrogen, deisel (or substitues), and gasoline (or substitutes). coupes, sedans, and I'd wager even small wagons/CUVs could be built on this platform.
I would expect to see Volt-derived technology leaking down onto other 'lesser' models within a decade, too. Same as performance goodies leak down from Corvette.
But DGthe3 still has a very good point, GM intends not just to beat Toyota at its own game; but to completely surpass them with a brand-new type of vehicle. And if revolutionizing the industry doesn't qualify......
I don't think anything does.