Physics Processing Units, Game AI and AI Cards

In short this article states that Intel (like AMD) is developing standards and interfaces to allow other companies to build accelerator cards that can interact very closely with the CPU.  This new technique will "improve the ubiquitous PCI technology to accommodate a wide variety of accelerator chips".  Now I'm wondering: in recent years more and more functions that used to be done by cards where integrated into the mainboard or even emulated by the CPU (think of the modems or  network cards for example).  Why now the movement to more specialized processing hardware? Will it be common for computers to have  a card dedicated to physics simulation (a PPU or Physics Processing Unit) in the near future? And an Game-AI card in two years? A real AI card in 5 years? And how would a real AI card look like, what kind of functions would it perform? Some analog computations? Very fast similarity based retrieval?