The ATI eXternal Graphics Platform (XGP) technology isn't dead yet. Legit Reviews reports they saw a demonstration of a Radeon HD 5830 graphics card with XGP:
ATI's XGP technology (eXternal Graphics Platform) is an external graphics solution for notebook PCs. ATI XGP is designed to deliver enthusiast-class graphics performance, true multimedia upgradeability and multiple connectivity options, revolutionizing GPU performance on a notebook PC equipped with an external PCI Express 2.0 connector. This video is of a demo system that they had setup at CES 2010 showing off Radeon 5830 graphics.