Yes to Qui-Gon and yes Mortis, if only as a dialogue reference. Qui-Gon was essentially what the Jedi should have been and he saw the corruption of the Jedi Council. He was quite wise, compassionate, trusting, and unorthodox; he didn't blindly accept what the Council said, who eventually lead itself to its own downfall. There's too much potential with Qui-Gon as a Force ghost and he could be a very good mentor to Luke, even better than his two previous masters. Furthermore, it'll give the writers a good reason to bring back Liam Neeson in a Star Wars film. Perhaps name-drop Mortis as a nod to the TCW fans. Plus, he could give an explanation as to who the Whills are. Like I said, too much potential with Qui-Gon as a Force ghost.