CONTAINS REAL AND POSSIBLE SPOILERS Nothing has been said yet about what will or won't happen in Episode VIII, Episode VII has just come out in the cinemas to good review and good numbers of people watching them. What I say here will contain some spoilers What we know is that the storyline will certainly follow Finn and Rey as they continue the fight against the First Order. There's been mention of an additional lead female character, could this be the character that Gugu Mbatha-Raw might be playing.
Whilst we know that Princess Leia and Luke Skywalker are returning, maybe Han Solo by way of back story. We know that Disney are planning on doing a Han Solo spin off movie or two in the near future but that will feature a younger actor and its joked along the lines of "When Han Solo met Chewbacca".
According to the Daily Mail, Kathleen Kennedy has said the entire cast will be returning, however can't see that given Star Wars penchant for killing off characters in films. Additionally, a classic character will be coming back according to Cinemablend, we can only speculate who that could be, possibly Lando Calrissian?