Right now, Epic Games is developing its upcoming free-to-play survival/builder/defense game Fornite for PC only. That could change, however, as an Epic Games spokesperson has told us that Fortnite "may come to other platforms in the future." That's all that was said to us, so take that for what it is.
As a free-to-play game, PC lends itself quite nicely to Fornite, but Sony and Microsoft have made tremendous strides in offering the free-to-play titles on its game consoles. On Xbox, we now have free-to-play games like World of Tanks. Meanwhile, on PlayStation, we have games like Warframe, PlanetSide 2 (coming to PS4 soon), DC Universe Online, and War Thunder, to name a few. So it's not like a free to play game on consoles is unheard of anymore.
As Epic explained durings a recent preview event for Fortnite, free-to-play allows them to reach "the maximum number of people." If reaching a wide audience is their goal, then it'd be smart to expand to other platforms once the game is established on PC.
Fortnite still doesn't have a release date, but Epic also said they will begin letting people into the game this year. "Even more players" will be invited in 2015. You can check out the recently released gameplay video here.