Variety is reporting that Paul Greengrass, the acclaimed filmmaker behind the last two Jason Bourne movies, has opted out of directing the upcoming fourth entry in the popular spy franchise. Matt Damon hasn't signed on yet either. The article suggests that if Damon chooses not to reprise his role that the franchise might undergo a total reboot and posits Duplicity director Tony Gilroy, who has writing credits on all three films, as a potential replacement for Greengrass. The Bourne movies have scored with critics and audiences alike and certainly survived eccentric The Bourne Identity director Doug Liman getting replaced by Greengrass for the sequels, so we remain, as always, cautiously optimistic.