Fortnite as Epic Games' first Unreal Engine 4 game, "exclusively for the PC," Epic Games design director Cliff Bleszinski took to Twitter this afternoon to make some breathing room. "We wouldn't rule out the possibility of other platforms later," he wrote. That is, while Fortnite will be "primary and first" on PC, it may not be exclusive to the platform forever.
Given that Fortnite is built using UE4, it stands to reason that those "other platforms" won't be of the current generation (none of Microsoft's, Sony's, or Nintendo's current hardware can run UE4-based games). What might they be, then? We'll have to wait until the next console generation to find out, it sounds like.