I saw a demo of one years ago that solved this by merely overlaying their own SDN/compute/etc. onto VMs in each of the supporting underlying clouds. So you did

I saw a demo of one years ago that solved this by merely overlaying their own SDN/compute/etc. onto VMs in each of the supporting underlying clouds. So you didn't even get the 'least common denominator', you got 'tied to one particular startups cloud definition'. I run away screaming at this stuff, generally.