Perhaps that's why I added a wink in my post?? I didn't want to go to deep into it, because of not wanting to add spoilers. But since that has happened now, I might as well add my two cents.
I certainly believe Kira is not dead. She is most definatly with the Prophets. However, right now, I'm not so sure if she's coming back or not. I kind of have the feeling she might actually stay with them for the long run. Don't why, a gut feeling.
I do however, believe that Vaughn is dead. Some people may feel he could return some way, since his essence saved Kira. But I really think that's it for him.