Of course, Driver also says he only has "one piece" of information, so it's possible that he may only know part of the end of the story. He doesn't specifically say what that piece is in regards to, it's easy to assume that he may know the final fate of Kylo Ren in Star Wars Episode IX, but he stops short of actually saying that. It's also possible that the "one piece of information" is actually just the ending of the entire trilogy, so he may know the fate of everybody.