This does not change what canon was before April 25, 2014 - if one takes George Lucas's definition. It also isn't a sign that all previously made works will be regarded as non-canon, or really completely disregarded: as the group that actually made this decision participated in the design of the Galactic Starfighter expansion of
Star Wars: The Old Republic. The goal of this announcement is to show that they plan on changing the
Holocron continuity into simply Canon/Non-Canon rather than a multi-level system.
Lucas has always said something like: The movies are the only thing I care about. I won't be held down by the EU.
Leeland Chee, who was in charge of organizing the canon continuity of Star Wars since 2000, has agreed with this statement for years. He created different levels of canon - which reflected upon this since the movies and TV show were above everything else.
The news and article titles such as, "All novels, games, and comics are non-canon!" is just sensationalist - either influenced by ignorance of what was Star Wars canon before the Lucasfilm announcement or by a desire for readers.
Anyone can read the very announcement by Lucasfilm.
How I see things happening after this announcement:
- The TV series the Clone Wars and Rebels will get bumped up to Canon along with all movies.
- The EU as it was before will be rebranded under Legends. Lucasfilm won't be restricted by Legends in the creation of future content - yet it won't ignore it completely. Lucas did the same when making Episodes I, II, and III. It will essentially turn into reference material and sources for the new era of Expanded Universe - sort of how the EU always has been due to how little of an effort there was to limit contradictions until recently.
- All future material will be a part of Canon except for novelizations/games/etc. going over content of the original version, which would be labeled under Legends. (ie. the novelization of Episode VII would be under Legends).
- What was non-canon now remains as such.