50 Cent says he'll retire if his latest album, Curtis
, doesn't outsell Kanye West's Graduation
. But if neither album does well, hip hop might face something even more daunting than the loss of a star. We talk with Sasha Frere-Jones
, pop music critic at The New Yorker magazine, and Greg Kot
, Chicago Tribune pop music critic and co-host of public radio's "Sound Opinions."