Marshall, when interviewed by Nerd Report and Collider as part of the TCA tour, briefly touched on the challenge of settling on a story for another Jason Bourne-centered film (a task that Damon once turned to Interstellar co-screenwriter Jonathan Nolan for assistance on).
“It was really the challenge of finding the story. If you look back five or six years ago, when we were maybe going on, we just didn’t have a story. It’s taken this long for us to come up with a story that everybody responded to. Now, we’re moving forward.”
However, Marshall once again emphasized that another installment with Jeremy Renner’s Aaron Cross (from The Bourne Legacy) hasn’t been abandoned and that the Bourne franchise is now on “separate tracks.” He also said, in a matter of fact fashion, that “We don’t have plans [for a crossover film]“ right now; though, Marshall didn’t rule out the possibility of Damon and Renner co-anchoring a Bourne movie one day (something he’s also expressed interest in during interviews in years past).
http://screenrant.com/bourne-5-damon-renner-goonies-2-script/