Sure can. HyperTransport with its tunneling approach is entirely modular and transparent from chip to chip. So when someone comes up with a HT-PCIE tunnel chip, you'll still be able to use a HT-AGP tunnel right next to it - very much like it's now done with HT-PCIX and HT-AGP tunnel chips on workstation boards like Tyan's Thunder K8W. In fact, you could have PCIX, PCIE and AGP all side by side on one single mainboard.