A new novel to tie-in with Rogue One called Catalyst is to be written by James Luceno:
Twitter: StarWarsBooks (Del Ray)
No release date yet, other than it'll be released in the fall of this years. I think it's absolutely fantastic news! Luceno is my favorite EU-author and in my opinion, he's able to catch the essence of Star Wars like few other authors can (Zahn comes close).