Many bothans died to bring us this information: The Star Wars Expanded Universe - or EU for short - is getting cut from Star Wars canon like hands get cut from the Skywalker family. In a news post on the official Star Wars site, Lucasfilm announced that only the six Star Wars films and the Clone Wars television show will be considered canon. In other words, as far as Luke, Leia, Han and the gang are concerned, there were no knights of the Old Republic, nor was the Force ever unleashed.
The Star Wars universe was previously structured under a multi-tier hierarchy system, where some events were considered more canon than others. For example, The Clone Wars' explanation for the origins of the Rebel Alliance were more true than The Force Unleashed's. How does that make sense you ask? We dunno. Cosmic bacteria or something, probably.
In any case, according to Lucasfilm, "all aspects of Star Wars storytelling moving forward will be connected." So from here on out, what you see is what the Star Wars universe gets. While that might be distressing for fans of things like Knights of the Old Republic or the Jedi Knight games, Lucasfilm is still keeping the EU around - in a sense. Stories from the EU will be printed under the Legends banner, and the teams creating new content are still drawing inspiration from the EU.
Elements first created for Star Wars tabletop roleplaying games will be seen in the upcoming Star Wars Rebels TV show, for example. So who knows, maybe Kyle Katarn - a character who made his debut appearance in a Star Wars video game - might still show up, albeit in a way that fits with Lucasfilm's new creative direction.