UPDATE: It seems that we were correct in assuming that this next piece of DLC will focus on the Burned Man. Xbox Live users can actually see the proof themselves. Go to the MarketPlace, search Fallout New Vegas, and select the Fallout: New Vegas Teaser Trailer (HD). The picture in the top right of the screen will then turn to the picture below.

The picture clearly depicts a man who has been badly burned and is wearing bandages across his head. Honest Hearts has also been the next rumored DLC to arrive but no one was sure whether or not that specific DLC would incorporate Joshua Graham's story. I'm sure it's safe to say that Honest Hearts WILL BE the next New Vegas DLC and it will contain the Burned Man within its premise.

The PC version of Fallout: New Vegas’ add-on Dead Money has some interesting info within its files. Fallout Wiki user Xporc, has discovered in the Dead Money BSA file a NVDLC02 snow globe titled Zion National Park. Snow globes being the collectibles for the Courier instead of the Lone Wanderer’s bobble heads. Each snow globe correlates with where it is found in game.  It so happens that the Zion National Park is located in the south west portion of Utah and in the scale of Fallout that is not far from the Grand Canyon.

According to Fallout: New Vegas lore, Joshua Graham was lit on fire and thrown into the Grand Canyon, by Caesar, for losing the first battle at the Hoover Dam. Legend has it that he survived the event and seeks revenge under the name the Burned Man. If that doesn’t, hopefully, confirm the next DLC’s plot…I don’t know what will. Luckily, all future add-ons are being released on all available systems (PS3, 360, PC) at the same time. The exact date of the next DLC has yet to be confirmed.

[Fallout Wiki]