Money. The show is cheap to produce and there is still an audience for it. ABC gave the show a second chance and Bill Lawrence didn't really think it would get a ninth season, thus making the eighth season's finale seem like a series finale. All we know now is that a John C. McGinley's Dr. Cox and Donald Faison's Turk will star, along with new cast members including one "big star" (according to Bill Lawrence). Zach Braff, Sarah Chalke, Judy Reyes, and Ken Jenkins will appear in a handful of episodes, but not in the main cast.