J. B. Smoove -- Curb Your Enthusiasm for Another Season of 'Curb'

Only Larry David knows for sure whether or not there will be another season of "Curb Your Enthusiasm" ... but co-star J.B. Smoove does not sound optimistic.

David is famous for keeping his "Curb" plans secret up until the last minute ... even from HBO and the cast. But Monday at LAX, Smoove sounded like a guy who didn't plan on portraying Leon Black again any time soon.