Final Fantasy XIII-2 is extending the story built in the first game, but we can expect the game to continue far past what you'll find on the disc. Producer Yoshinori Kitase has revealed that the game is planning plenty of downloadable content, and estimates roughly one or two packs per month.
The Japanese magazine Dengeki PlayStation (via Andriasang) reports that each of the packs will contain multiple items, for an undisclosed price. Kitase promised the content will strike a good balance between price and quality. And while none of the packs have been detailed, we know that costumes, weapons, and enemies are among the goodies you'll find in the packs. Square Enix is currently working to make downloadable costumes work inside cutscenes.
These plans are for Japan, but it's likely North American plans will be similar.
The magazine also details the "Summon Raid" and "Syncro Drive Gauge" systems -- keep in mind, those are translations and may not be the final names in the North American release. The Summon Raid lets you capture monsters in battle according to a crystal percentage. Meanwhile, the Syncro Drive Gauge lets your monsters unleash a powerful attack once it's full, and these attacks will sometimes include quick-time events.
Final Fantasy XIII-2 is due on January 31 in North America.