Re: the Star Wars Expanded universe
Any backstory stuff in the new movies may conflict with the pre ROTJ EU, but a lot of it should be O.K.
The new post ROTJ continuity will almost certainly cherrypick chunks of the old EU but it will invalidate the general direction of the novels.
I reckon Chewie will be back, Han and Leia will have different children, the Vong won't exist and I'd expect to see Mara Jade...
Soon oh soon the light, Pass within and soothe this endless night, And wait here for you, Our reason to be here...