In a recent interview with Rock, Paper, Shotgun, Epic Games producer Tanya Jessen mentioned that a constant online requirement (not unlike Diablo III) for the upcoming PC game is a possibility, but is not something she is willing to confirm.
"That’s something we don’t know yet,” she said, adding, “It’s gonna be really dependent on gameplay, and it’s also dependent on platform – the method of getting updates and stuff like that. So I can’t say for sure today one way or another [whether or not we're going to use it].”
Jessen went onto say that Fortnite is being developed with its multiplayer firmly in mind, revealing,
"Fortnite is a game that’s being developed as a co-op experience primarily. That’s our number one focus. This is a game you’re gonna want to play with your friends, and it’s most fun with your friends. So whatever we decide to do there is gonna be more relevant to the most fun experience you can have with your friends [than it is to piracy]. But I can’t nail that down today.”
Nothing has been set in stone, however. Epic later issued an official statement saying that concerted discussions regarding an online requirement have not even taken place. Epic wrote,
"We’re not talking about our plans at this time, mainly because that plan doesn’t exist yet. Fortnite is an iterative, living project and many things are still being decided prior to its release in 2013.”