At least, that's our take-away from developer Obsidian's recent AMA on Reddit. In fact, we feel a bit dirty even calling this 'DLC'. It's an expansion pack, just like back in the good old days *shakes cane*.
Says Adam Brennecke, executive producer and lead programmer on Pillars:
"We are looking at doing an expansion that's about the same size (area-wise) of [20-30 hour Baldur's Gate Expansion] Tales of the Sword Coast . I won't reveal much about it since it's early in development, but we've already have a small team working on areas and environments while the rest of the team focus on shipping the game. We will announcing more things about it over the next few months."
Brennecke also made reference to a Pillars sequel, building on comments made in February by Obsidian CEO Feargus Urquhart. Surprise surprise, it looks like it'll be another crowdfunding project:
"I would say crowdfunding is pretty awesome. We wouldn't be here making Eternity, and many great games in the past couple of years wouldn't have been made if it weren't for Kickstarter. After running the campaign and going through development, we've all learned a great deal on how to better manage stretch goals, on the ins and outs of fulfilling physical goods, and what backer tiers were received well (for us and for the backer). When we do Kickstart another game (or the sequel) we collectively have a lot of new ideas for stretch goals, rewards, and new tiers that should make the crowdfunding campaign that much better."
You can read more of the Pillars subreddit's pick of the AMA here.