Regis Philbin -- I'll Be Gone In November ...

November 18, 2011 ... mark the date -- because it will be the LAST TIME Regis Philbin will host "Live with Regis and Kelly."

80-year-old Regis made the announcement this morning -- but there's still a HUGE mystery ... no one knows who his replacement will be.

There are a handful of fill-in hosts who are rumored to have a shot at the gig -- including "Dancing with the Stars" alum Psycho Mike, "Survivor" host Jeff Probst and Howie Mandel.