this movie is not a romance but about Bruce and coming to terms with where his choice to be Batman has led him, and so the interraction with Bruce/Selina Bat/Cat romance/connection serves its place because Selina's character is also looking for a fresh start away from her mistakes and misfortune, and their 'romance' isn't something that is really hammered home with a mallet. (Let's face it, Romance onscreen isn't one of Nolan's strong points) It is there, hinted at, a connection shown, a ying and yang and a spark, that's clear,--they share two kisses--both initiated by Selina, and yet she also lures him to Bane where he is nearly killed but then saves his life later, so the end is there for people to go with and interpret however they see fit as far as what else might transpire between these two complicated characters.
All this talk is really about a scene that is described as 3 seconds long with Selina not being the focus but moreso Bruce, and again the nod to Alfred calling back to their earlier chat and again showing Alfred that Bruce is alive and will be 'okay'. Yes, it is closure that Bruce is hanging up Batman and will in fact be living 'a normal life' (as normal as one can be given his past and personality) whereas the same can be said for Selina. I think that's where the splitting hairs come in. Shippers in the Bat/Cat camp will see it as finally the two settling down forever because they have no more barriers, but others who are more focused on Bruce's inner motivation and character as a whole (outside romantic endeavors) may doubt he (and arguably Selina) are capable of ever being domesticated in the manner most of us are familiar with. Even if despite the fact that the obstacles that keep them apart are removed, they may in fact learn that was which also connected them. I think even Bale hints in his interviews that Bruce would never really ever hang up the Bat because he seems to be game for another if Chris finds the right script--even mentioning The Dark Knight Returns as an option when he gets a little more up in years. And they do make a point in the movie to mention that the Wayne Estate can't be closed so there is also that hint...