These current titles are really only showcasing prettier visuals(and yea some sound and network features otherwise impossible) but it's really just the pretty graphics that are the showcase. The Witcher 3 will, undoubtably be the game that showcases MUCH more. It'll show why these consoles were necessary in order to create this vast living world. 
Ill put it this way, as good as Killzone and NBA and Ryse may look or sound, those titles could probably be down scaled to run on the last gen systems(hell NBA already is) and roughly be the same. That is impossible with the Witcher 3. If they were to do that the game would be COMPLETELY different and it's why they didn't even entertain the idea of putting this game on the WiiU, 360 or PS3. Those last gen consoles would force them to completely abandon their vision.