Zuckerberg, speaking in a Q&A with Bloomberg Business published today, said Facebook's user base is now large enough that the majority of customers at other sites -- like Skype or Netflix -- are likely also using Facebook. That means those large-scale services can now rely on Facebook as a "piece of critical infrastructure for registration."
"But the bigger question is, what services can get built now that every company can assume they can get access to knowing who everyone's friends are," Zuckerberg said in the interview. "I think that's going to be really transformative. We've already seen some of that in games and media, music, TV, video, that type of stuff. But I think there's about to be a big push in commerce."
Some other areas that may someday be tied into Facebook include health care, finance, and government.
And Zuckerberg again hinted at, saying that "at some point, that will start to be a better map of how you navigate the Web than the traditional link structure of the Web."
Meanwhile, Zuckerberg wouldn't predict when Facebook would hit 2 billion users, but said it will largely be tied to mobile. And he expects to make more money per amount of time that people are spending on mobile.
He also hopes to enter the Chinese market at some point but said "we need to show we can do it in a way that's going to make everyone happy, including ourselves."
Zuckerberg also called the market's reaction to Facebook's IPO "disappointing" but said the company is working to make "the company worth as much as possible over the long term."
He said Facebook is focused on moving quickly, even as the number of engineers rises. But Zuckerberg said that means Facebook makes more mistakes than other companies.
"You can't have everything so you just have to choose what your values are and where you want to be," Zuckerberg said. "For example, Microsoft has a huge focus on really rigorous, bug-free code. That's cool. I think that's the right decision for a lot of the markets they're in. But for us, this is the right way to go."