Epic games revealed that it is working on a "competitive online action game" via a job listing posted on its website. The studio is currently looking for a Senior Systems Designer to work on one of two projects; one is Fortnite, the co-op survival action game, but the other is for a currently unannounced title.
The job spec describes the game as a "...competitive online action game that includes player progression, heavy itemization, and a dynamic economy." There's no other information aside from Epic looking for candidates that are "passionate about playing and/or building Shooters, MMO's, RPG's and RTS games."
Whilst any guess would be pure speculation, it wouldn't be a stretch to imagine Epic working on the foundations it's laid with the Gears of War franchise. An online, persistent shooter? Doesn't seem too crazy but this is an Epic games without key staff like Cliffy B so who knows in what direction the company may be headed.