Of course it will be a mix, but not a mix in the same die, at least not for performance and high-end markets. That would be a suicide, a GPU die is already big, later CPU dies are too, a mix would be imposible. Imagine a 1000 mm^2 thing that has a 400w TDP. No way. But right now if you have to spend $500 on a CPU and a GPU, if you are a gamer you will spend $200 on a CPU and $300 in the GPU, but if you are a scientist, video editor or an economist(lol) you would usually spend $450 on the CPU and $50 on the GPU. In the future it will most probably be $150 and $350, respectively, if not even more in favor of the GPU.