If Epic are going to make a new Jazz game, it will likely use the Unreal Warfare engine. (The engine used in UT2k3, Unreal 2 and the like). The upside is that with Epic at the helm, the game will be a butt-load of fun, and the game will be more accessible to the first-person-shooter types. The downside is that level design will be very hard, and it'll require a working knowledge of 3D Modelling to make truly great levels. At least we won't be restricted by "tilesets" anymore, but by the allmighty framerate.

Oh, and people will be able to code new stuff in, in UnrealScript. Rock!