Having Anne Hathaway as Catwoman in DKR is at the very least a great way to leave the door open for her to headline a Catwoman movie, if the bean counters decide that she's a viable character for her own film. She's a young but established talent, and the movies she's headlined have done great at the box office. Box office viability was one of the big reasons a lot of people had her as a contender for a hypothetical Wonder Woman movie. They couldn't have picked a better actress to carry a CW movie, even if that was not necessarily the motive.
Also, I'm sure EVERYONE is going to be buzzing about Hathaway after DKR. Not to the extremes that they were with Ledger (like it or not, Joker being a posthumous performance was a contributing factor), but it's a huge role for any actress to land. The demand for Hathaway in movies is only going to go up after her being in DKR, and she quite likely has an Oscar win somewhere in her future (she already got nominated for one in 2009).
Ignoring the Halle Berry disaster, from a business POV a true Catwoman spinoff movie would be a great way to cash in-- Batman is a colossal film franchise, and after DKR, Catwoman is going to be everywhere, especially once Halloween rolls around. If they have a popular character in a huge movie franchise played by a popular actress who is capable of headlining successful films on her own, it would be an ideal time to capitalize. Even on a "small" budget, as long as the script were there they'd stand a good chance at bringing in a good profit for the studio.
One of the tricky things is, what would they call it? "Catwoman" is already taken (unfortunately), but as The Dark Knight proves, sometimes you don't need something as straightfoward as using the main character's name. Personally, I kind of like "The Nine Lives of Catwoman." "Selina's Big Score" worked nicely for the graphic novel of the same name, however I doubt the film will be a direct adaptation of it.
Also, another thing that a Catwoman reboot could give the fans: the "Nolanized" version of Black Mask!