Source: http://www.siliconera.com/2011/11/21/after-30-hours-of-final-fantasy-xiii-2-whats-next/

In an interview with Famitsu, the Final Fantasy XIII-2 team said the game’s story is between 30 and 40 hours long. What happens after you complete it? You can reload your cleared save data and warp back to the point right before you fight the last boss.

Final Fantasy XIII-2 will have a lot of additional content released as DLC, the first pack being the Omega boss battle in Japan. More boss battles will are planned as future DLC. Square Enix will also release additional costumes. Some of the DLC will be free and other items will be paid. Select items will be pre-order bonuses like the Genji Bow, a special weapon for Serah. The publisher says they have no plans to distribute these digital items any other way. Square Enix planned enough DLC to keep Final Fantasy XIII-2 going until spring 2012 with monster or enemy packs released every two weeks.

Have Final Fantasy XIII save data? That will unlock an in-game item, and according to Famitsu players will get some kind of wallpaper.

Is that just the main story, or does it factor in side missions?

No it does not, so there is more where that came from.

They could have said Versus XIII but nooooooooooooo... >_

It really reflects poorly on whoever links such an atrocious article to VGChartz.

Was that written by a 5 year old?

30 to 40 hours main story isn't too shabby. Iirc X-2 took me roughly 24ish (though I have a 90ish hour save file now due to getting about 94% completion) hours and I remember complaining about that the night I finished it. Though XIII-2 is looking to have a good amount of extra content so that should keep me occupied until I obtain my Platinum.

There was an important point mentioned on another article.

The DLC is being made by a separate team of young designers, this will allow them to make DLC while the main XIII-2 team moves on to their next game.

Ugh, side quest as DLC...

I wonder if they count the multiple endings in as the main story as well. I'm sure we will have to go back and rewrite key elements in the story to unlock these endings. I'm sure for most Platinum hunters this game will exceed 70-80 hours.