The 'Dark Knight Rises' DVD hasn't been officially announced yet but the current rumor is that the DVD and Blu-ray will include a "Director's Cut" that will include the heretofore unseen origins of Bane.

Nuke the Fridge is reporting that Warner Bros. and Nolan are working on a Director's Cut DVD that will include 30 minutes of new footage, specifically the origins of Bane and extended fight sequences with Ra's Al Ghul (Liam Neeson).

While this should be taken as a rumor - 'The Avengers' was also rumored to have a Director's Cut, which was eventually debunked - there definitely is a considerable amount of Bane's origin that was cut from the film. Says costume designer Lindy Hemming:

He has this scar from the back injury. Even if he hasn't got the bulletproof vest on, he still has to wear the waist belt and the braces. In that scene in the prison, where he's learning to fight the same way Batman learned to fight, he's wearing an early version of his waist belt. It's showing support, but it's not the finished one he eventually wears. He's also wearing an early version of his gas mask, all glued together....There's a whole early section for Tom Hardy where he's fighting and being taunted by people. He's got chains on him, and he's standing on a wooden thing while people are attacking him. And in that scene, he's wearing a much more ragged, primitive version of the mask. There was another section that showed you why he had the mask and where it came from.

So there is footage of Bane's origin that exists and it seems likely that would be included on the DVD and Blu-ray but will Nolan actually edit it back into 'The Dark Knight Rises' and make the 2 hour and 35 minute film over 3 hours?

It seems unlikely and we'll put our money on a bunch of deleted scenes instead (Christopher Nolan, perhaps as much as anyone, has the clout necessary to release a "Director's Cut" in theaters - it's not like Warner Bros. was forcing him to make edits...).