Intel has methodically integrated more of the system on the CPU package. With the memory controllers, integrated gpu and pci-e controllers already on the CPU, and VRM and rest of the north bridge following in Haswell, there will be nothing of value left on the motherboard. Broadwell-era motherboards will be dumb connector boards worth $50 at most. That's why they can be sold integrated.
Still, it's kind of an annoyance just because the form factor of the computer is still so closely tied to the motherboard, even if the board itself is trivial. Are they going to get a ton smaller and just be CPU+RAM with cable ports for PCIe/USB busses?
You cannot really do full-speed PCIe buses on cable ports.
I expect that Intel will do what AMD and Nvidia are doing presently with GPUs, and what they used to do with their chipsets: Sell the CPUs into the various motherboard manufacturers, and let them sell the complete package to the consumer. They can implement any form factors they like.
Of course with a sufficiently punitive contract that Intel retains control of everything.
