Honestly, I see not much changing at all. Console games will obviously be heavily optimized for MT/MC, but PC ports probably will not be. It will be the same as the current situation with PC ports.
I'm going to have to disagree with you on this one blackened..
These new game engines (Frostbite 3, CryEngine 3, Disrupt, Unreal Engine 4 etcetera) are all
inherently designed to be scalable across different platforms, ensuring the titles that use the engines run optimally on each platform whether it's the Xbox 360, PS4 or PC..
So whatever multithreading optimizations are present in the console versions, will also be present in the PC version and vice versa.. The Unreal Engine 4 is rumored to scale all the way up to 16 threads I believe.. I have no idea how many threads the Frostbite 3 engine can handle, but I'm sure it's at least 6, and more likely 8 or more..
Game development will change with the advent of the new consoles, since they are all x86-64 with the exception of the Wii U, which is irrelevant. The PC will become the lead platform on a regular basis, and then games will be downscaled for the consoles because not only is it easier to develop from the top down, but ensures that the PC does not get a sub optimal version.
We see this already with upcoming Ubisoft titles like Watch Dogs and Assassin's Creed IV, where the devs are on record stating that the PC is the lead platform. For Battlefield 4, the PC will also be the lead platform.
Any developer that cannot implement proper multithreading support in their game engines will find it extremely difficult to compete, because multithreading is not only necessary to tap the CPU power of the upcoming consoles, but is also necessary due to naturally increasing game complexity.
Games like Watch Dogs or the Witcher 3 that feature open World gameplay with increased detail and better A.I over last generation's game will naturally require more grunt from the CPU..