This NewsFactor article discusses an upcoming technology designed to replace PCI/AGP... and probably involvement/support from Apple:
Now, Apple may be poised to push another standard called 3GIO, widely heralded as the successor to PCI and AGP expansion slots. Those slots, located on a computer's motherboard, allow insertion of video cards, networking cards and so on to enhance the computer's capabilities.
The new standard (3GIO) is expected to be introduced in 2004 and provide faster performance than current standards.