All of that is relative. Randy may not believe the world will end on the 21st (It will not by the way). I do believe that we will get new DLC in Dec to compete with other games etc...
^ This. Was reading article on line yesterday where he had Twittered overweekend again confirming Level cap was planned in future DLC, looking at increasing bank storage and finding new uses for Eridium.
They did the season pass for a reason. They probably have almost all 5 DLC's developed and just fine tuning.
Wouldn't suprise me if they didn't do a christmas themed DLC with cursed elves, reindeer skags. Goliaths with stocking heads etc. Could be called Moxxis Holiday's or something weird.
Given their track record, I think they should worry about giving us a bug free DLC than putting one out every month. I could stand to wait until next year for the next DLC if it didn't have all the problems the last 2 had. Maybe Gearbox will develop it themselves this time?