Kingpin's rights are owned by SONY right now since he is considered a Spider-Man villain. Not exactly sure how THAT works.
The Kingpin has long been associated with Spider-Man. He even debuted in an issue of The Amazing Spider-Man
In my ideal comic book movie world, I'd like to see Spider-Man, Daredevil, and maybe the Punisher all grouped together under the same studio (maybe along with Marvel's other "street level" heroes), the X-Men and their universe off on their own, and the Fantastic Four grouped with the Avengers and their related characters.