Not so much a nail in the coffin, but a kick to the side.
The current "established" (I use established as loosely as I can) post ROTJ cannon is just not a matter of cannon anymore. It is now just a different set of stories. Like how in Marvel you have the Age of Apocalypse timeline, and the Days of the Futures Past timeline, and The Ultimate universe. It doesn't remove those books from existence, it just makes them their own "timeline".
People just have to get over the whole THIS IS CANNON! thing. The only person that can establish cannon is the current person/people in charge. There is a good chance that they will take things they like that already exist in the EU and mesh them in with the things they want to create.
I would think they could throw the EU fans a bone or two because there are EU characters with pretty significant followings like Mara Jade and Thrawn (though sounds like he's been pretty much ruled out).