Marketing people would never let this happen. It is only in their interest to keep the 18-month turnaround on GPUs going. Even if it makes great engineering and production sense, linking GPU to CPU would translate to fewer units sold over longer periods of time. The lifeblood of the GPU industry is the ability to hawk new chips every year, and new boards every six months.
Don't be surprised if AMD breaks-off the graphics side of ATI into a separate company. They're after engineering tech and motherboards here. And selling the GPU side of things would help pay for the aquisition.