Oh, Lordy, they're gonna make a 4th Bourne movie. The first 2 were great, the 3rd only ok, but now that they're out of books, what's left? I have an idea:
Rather than focus on plot, just leave a film camera lying around and trained roughly on Matt Damon. Hire a bunch of street thugs to then come and beat the camera with sticks, bats, cudgels, etc. Then, take the camera and throw it off a building, but make sure Matt Damon's still visible somewhere in the shot.
Finally, put the camera in a car and wreck it on the highway.
I think it would work: the herky-jerky filming style that we've put up with for the last two movies would be maintained, and the movie would make about as much sense as the most recent Bourne.
Oh, and of course, Matt Damon has to survive everything. Maybe there could even be a brief scene with him being irradiated while flying a small plane into the top of a nuclear reactor while being eaten alive by evil top-secret government snakes. And live!