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".
I agree, from what I know of the post-ROTJ EU - it seems a bit of a mess. There must be hundreds and hundreds of stories from hundreds of different writers all trying to get a slice of the Star Wars universe. Of course some are better than others, e.g. The Thrawn Trilogy, but some of this stuff needs to be swept aside so writers have a cleaner slate to work from.