Here's a link to some Crysis videos, watch "Trailer and CryEngine 2" and "Tech Demo" to get an idea of the engine used for the game's graphics and environment interaction: http://media.pc.ign.com/media/694/694190/vids_4.html
Jeff Strain said something about Nightfall being the game that ties together the ends of Prophecies and Factions, which could've implied a new Guild Wars coming out next year. If so, ANet could use the Crytek engine to enhance not only graphics, but gameplay, with the possibility of allowing players to interact with the environment. For example, a ranger with Ignite Arrows could start a small fire that spreads a meter or two from the enemy target.
Naming it Guild Wars II would be appropriate to imply the chronology from the original Guild Wars to the new version. (Similar to World War I and World War II). If ANet could then bring current Guild Wars characters to the new game, with all of our items, armor, gold, etc, completely revised with the new engine, it would be a great experience.
Doing all this would most likely cost ANet, endorsing the new engine, recreating character models, environment, etc, getting new servers, but I strongly believe that a game like Guild Wars with the graphics and environment interaction of the Crytek engine has the potential to double the sales of the original Guild Wars, and win over a few WoW players.

Flame on.