Posted to Trello are future work items concerning effects, rendering, physics, animation, blueprints, AI, tools, platforms, VR, and other areas. Users are able to vote on the items they would like to see within UE4.
Having a native UE4 Linux editor ranks highly under platform work while the items in other categories vary from audio localization support to improved multiplayer handling. Take a look for yourself on Trello if interested in the Linux/SteamOS-friendly game engine.
Don't forget that just in a few hours we will also be learning more about upcoming Unreal Tournament plans by Epic Games.