In a Q&A at Kotaku, CEO Randy Pitchford answered fan questions about Borderlands 2, one of which concerned upcoming DLC.
Randy Pitchford, CEO of Gearbox, subjected himself to fan questions this week about Borderlands 2. Some of the information concerned things like level-scaling, vehicle options, Wii U games, the possibility of Borderlands 2 on the Vita, the problems with the Russian version of B2, what his favorite games are, and more. One of the more interesting topics was when asked what the current release plan was for DLC, Pitchford had this to say about Season Pass and non-Season Pass DLC planned:
The stuff we're planning and working on for the Campaign DLC Season Pass is big DLC stuff - more like Knoxx. We're extremely far along with the first campaign DLC. The second DLC is also in amazing shape. The third DLC is a little farther out and the fourth DLC is just in the pre-concept stages. We will have other, non-season pass related DLC. The additional character (Mechromancer) is one kind of example. The Borderlands 2 team is fired up at the moment. Customer love for the game is driving us wild - making us want to do more and more stuff. So, expect that there will be even more beyond the big Campaign DLC in the Season pass and the add'l character. We'll announce more stuff as soon as we are able to be confident in the commitment of the details we share.
And further clarifies later when asked about details:
Mechromancer is a new character. Things like new weapons and enemies will come in campaign DLCs and other DLCs. The big campaign DLC's are currently available at a discount with the "Season Pass" which is available at select retailers or on Steam. I believe you can also purchase it in-game. I would not be surprised if the Season Pass option is no longer available once the first campaign DLC becomes available.
Check out the full Q&A on Kotaku if you are interested in more from the Q&A.