In an interview with Gamasutra, Epic CEO Tim Sweeney revealed that Unreal Engine 4 is intended for platforms that haven't even been announced yet:
Gamasutra ran an extensive interview with Epic CEO Tim Sweeney on Monday. The executive shed some light on the next generation of the Unreal Engine, even offering tantalizing hints about the next round of video game consoles. “We’ve started a behind-closed-doors showing of the engine to developers; this is part of our very early ramp-up cycle,” said Sweeney, “We went through this cycle with Unreal Engine 3 starting in 2003 and 2004. At some point we’ll make public announcements and ramp up to the point where developers are shipping games, but it’s very early right now. We’re aiming very high, and the intended platforms this is aimed at haven’t even been announced.”
Given the fluid, always evolving nature of PCs, it isn’t a very big leap to determine that Sweeney is discussing the Unreal Engine 4 as a platform for development on the next round of game consoles, namely the PlayStation 4 and Xbox 720. Sweeney said that it’s still early to be showing off Unreal Engine 4 to the public, but Epic told the press in March that it hoped to show off the engine to public by the end of 2012. This was just after the engine had been demoed privately for developers at the Game Developers Conference.