I reading this article. I could see giving 10 or 20 year deals, but why in the hell would you give a studio the sole right to make your product in perpetuity?
IMHO when Disney purchased Marvel for 5 billion dollars, they bought a well-dressed up pig. While Marvel does own a ton of characters (approx. over 5000), a few of the most well known and successful characters such as Spider-Man, The Fantastic Four and the X-Men have homes at other studios. Sony of course has Spidey and 20th Century Fox, besides having the entire X-Men Universe also controls for perpetuity Daredevil and the Fantastic Four (includes the Silver Surfer and Elektra).