Last August, John Carmack confirmed Doom 4 was in development, but didn't divulge any details beyond that. He wanted to avoid what happened with Rage, where the game was shown extremely early in development and didn't quite match everyone's expectations. Since then though, everything has been pretty quiet, and now we may know why. It appears as though Doom 4 has been shifted to next-gen in order to better mesh with what gamers expect out of the series.
Speaking in a recent interview, Bethesda's vice president of marketing and public relations, Pete Hines, had the following to say:
An earlier version of Doom 4 did not exhibit the quality and excitement that Id and Bethesda intend to deliver and that Doom fans worldwide expect. As a result, Id refocused its efforts on a new version of Doom 4 that promises to meet the very high expectations everyone has for this game and this franchise. When we’re ready to talk about the Doom 4 Id is making, we will let folks know.
Doom 4 has apparently going through a total reboot since it was initially announced way back in 2008. It was originally going to be a reimagining of Doom 2, just like how Doom 3 was a remake of the first game. Your character in Doom 4 would eventually be forced into joining the Resistance, a band of civilians and military, in order to fight the rampaging demonic horde. There were plenty of scripted events along the way, which led to some members of id Software to refer to it as Call of Doom.
If that doesn't sound too enticing, don't worry, id leadership decided to reboot the game near the end of 2011. The game had been ignored for some time while work was finishing on Rage, so when the executives saw what Doom 4 was like, a reboot was in order. It was also a way to give the Doom 4 team a better sense of direction, which was something that was previously lacking.
As for Rage, a sequel was underway soon after the game's initial launch. Unfortunately, a less than stellar reaction from gamers and critics alike meant ZeniMax, parent company of Bethesda and id, needed to rethink its plans. Over the next several months after Rage's launch, it was decided to scrap the sequel and shrink plans for DLC. Eventually the Rage team was merged with the Doom 4 team to focus on the latter game.
More problems came about after the team merges, though, with managers from both vying for control over what Doom 4 should entail. Some ZeniMax executives believe Doom 4 should be just as big as Skyrim in terms of sales and culture, where basically everyone had heard of it.
Still, the issue remains that Doom 4 is a relatively unknown commodity at this point five years after it was announced. If nothing definitive surfaces in the next year or two, there could be changes at id Software. There's even a chance the studio could be gutted and refocused to only work on game engines like Id Tech 5. Hopefully that doesn't happen and Doom 4 sees the light of day, but we just have to hope something comes about at QuakeCon one of these years.