TPU reports Intel's future 14nm Broadwell will be a true system-on-chip (SoC), the multi-chip module will feature the CPU and northbridge in one die and the PCH on the other.
You can expect it by 2014-2015.
It began with transfer of memory controller from northbridge to CPU die (45 nm "Bloomfield"), and transfer of the entire northbridge to the CPU die (45 nm "Lynnfield"). The graphics northbridge transferred a little more gradually, first as multi-chip module with a separate CPU die (32 nm "Clarkdale"), then complete integration with the CPU die (32 nm "Sandy Bridge"). All through, the southbridge, or I/O controller hub (ICH) remained outside the CPU package, with the addition of a display output logic, it transformed into a "platform controller hub" (PCH), which is still just a glorified southbridge. Naturally then, such a drastic relocation of system components will warrant a socket change.