Oh, this thread will be pure speculation unless we've got some serious insider knowledge...
Just guessing myself, but I'm not sure if we'll see a CAAD10 at all. Maybe Cannondale could continue with an all-aluminum frame and end up with a tweaked '9, sure. But, with the "top" CAAD9 only having a 105/Ultegra mix, and every other "elite road" (their category) bike being either full carbon or a carbon/aluminum mix, I'd think that the quarter-century of Cannondale aluminum is coming to a close.
Guess we'll be waiting for the '09 catalog to come out.