In a recent interview, Epic Games vice president, Mark Rein, revealed that while they certainly will do another single player Unreal game, they are not currently doing so.
"I'm sure that at some point in our future we will make another Unreal, single-player, story-driven game", said Mark Rein. "I'm sure at some point there will be one. There are no plans to do one today."
"I think we've been really happy with the multiplayer-oriented Unreal Tournament. Despite what people feel, people get this crazy idea that if you don't sell five million units it isn't a success, but we heard today that we've shipped over 1.2 million units of UT3, not even including the Xbox 360 yet. We make good money on Unreal Tournament, and it's a good game that we love to make, and it's not a five-year-long production and it's a great test-bed for lots of cool things that we want to do. We like making this type of game, and we have Gears of War as our kind of vanguard, single-player graphic showcase type of game."