While it's now non-canon, i would guess it entirely possible that some concepts from the Expanded Universe could be used in the future of the franchise. Probably not with stories happening after Return of the Jedi, but probably some of the past events prior to the prequel trilogy could still be used. One example of this is a character named Darth Bane, an EU character who had a brief scene in one of the Clone Wars episodes. Clone Wars is considered canon at this point so Darth Bane is as well. If his story is ever expanded upon in the future, I would expect it to take some different turns here and there, but the character and original purpose were kept intact (notably being the creator of the "rule of two"). We'll see however.