I quite liked Legacy but the thought of a Damon-starring, Greengrass-directed Bourne movie is infinitely more exciting than that of a Renner-starring one directed by Justin Lin. Which I imagine is probably dead in the water now, unless Universal want to turn this into a sort of 'expanded universe' franchise.
When this is released, it will have been 9 years since Bourne's last appearance and 3 since Renner's in Legacy (which is largely set at the same time as Ultimatum). I wonder what time-gap there will be in-universe and what the plot will be? Will Bourne now be in a relationship with Julia Stiles, which seemed hinted at? And what of Pamela Lanney, who ended up in a bad way in Legacy?