I think that Dana would easily leave, however, Terry wouldn't really want her back. I think that being Batman means more to Terry than Dana. He'd be unselfish and want the best for her and the best for Gotham which would be him as it savior. Terry's preception of being Batman has changed. Initially it was to get revenge against Derek Powers and to atone for his past. Now I believe that he's settled into the role of the Dark Knight. And having learned from Bruce that role doesn't include Dana.