Another new preview
In this preview by TeamXbox, it is stated by Randy himself that the main storyline is about 15 hours long. I'll take that!
Another interesting quote from Randy:
"When asked about whether Gearbox is designing the game to facilitate downloadable add-ons after the game ships, Pitchford said that there’s “nothing definitive yet,” but claimed that there’ll be DLC releases for the game “based on what the audience wants.” We already can’t wait to make a run for the border."
Based on what the audience wants, just like having more than 4 player pvp. Cool.
Those are like sidequests to enhance your enjoyment of teh game. They don't change the story, but could add to your knowledge of Pandora. And I hope you're right about the DLC.
I really hope that they won't charge for the DLC... That would be pretty bad. That's like charging for stuff that should already have been in the game.
If they put everything in the game that they should, they'd have to charge like $100. But even then, I'd get this.

There are say 30 storyline missions, so that's half an hour give or take per mission. Multiply that by 140 other missions and that's another 70 hours. That's 85 hours of missions alone! I love it!
"What I've felt, what I've known, never shined through in what I've shown. Never be, never see, so I dub thee: Unforgiven." -"The Unforgiven" by Metallica