Ya know let Renner do his thing.  Matt is not needed right away. I'd pump out a few movies with J.R. Then worry about bringing back Matt.

This movie won't fail.  If the most recent (I think) trailer's awesomeness is any indication, people will be checking this out.  I think it's also a smart movie to have the story interwoven with Ultimatum as it will naturally draw the fans of the original trilogy into this flick.  Then there will be all the people who go because Bourne is in the title but have no idea it's apart from the Damon movies.  

Do a Renner trilogy, then bring Damon back for the 7th. Or, have Damon and Jimmy Kimmel make a cameo at the end of the 5th where Kimmel says "My apologies to Matt Damon, we ran out of time for you to be in this movie..."

I too agree with the thinking that this movie won't fail.  They have done enough, based on the trailer, to tie it to the Bourne universe and right now Renner is pretty bad ass and popular.  They should get 2 movies and then try to bring Damon back for a cameo or co-star role.

If they wait too long, Damon will be too old to play the part well.  Just sayin

I don't know about legacy, I like Jeremy, but I do like Matt also. The trailers I have seen for this movie just make me they are trying to tell the story all over again. I don't see it doing as well as people will think. However I think Jeremy is going to still be a hot ticket since he just starred in one of the biggest movies in history and the biggest movie so far of this summer. So only time will tell what will happen with this almost like Total Recall these both are sort of wildcards.