I've just been reading that ICS won't even be on ANY devices for some good number of months - and that upgrades for existing devices will come along (for some and when/if they do) "sometime" after that.
Meaning there still won't be ANY meaningful number of tablets to even host decent tab applications for at least a year or two - and a phone base mired in the 2.x's - not even 3.x and let alone 4.0.
Which makes Dr. Schmidt's basic math a weee bit suspect.
The only reason 2.3.3 Gingerbread is at 50% making Android look like a unified and homogeneous mobile platform is because it's been allowed to stagnate for over a year. All that effort was moved to 3.0 Honeycomb which was only for tablets, which aren't selling, and then eventually locked down. Once ICS get going in it's drawn out focused manner we'll start seeing Android OS numbers all over the field again. I had hoped Google would have finally gotten this squared away but I guess not. This will end up hurting them on the high-end of the platform.