First off, in most of canon, books are rarely considered canon. (ie: Star Trek, etc) there are a few exceptions, like Babylon 5 where JMS took an active hand in things.
But frankly, I am so so so thankful that they are NOT doing the whole Skywalker Twins, Thrawn, etc. I never liked where those stories went. And so while you may be disappointed. I am sighing a huge sigh of relief.
And retcon, was the silly stuff they did in the prequels. I think JJ Abrams will be a bit more mindful. That said, I kind of would like to see some soft ties to a few of the prequels. Aliens pictured...or about the Gungan genocide that wiped out the entire race. Etc.