Let's see Grunt blast a Baron full of buckshot. He'd probably turn tail screaming. I remember reading that when Quake was introduced, and yet here we are with the next Doom on the horizon. Id software is unique in the gaming community in that it began the trend of allowed modification to it's games by those who play them. This started with Doom, with people making their own maps, TC wads, and dehacked patches.
Doom fanbase out there.
We see numerous attempts to remake Doom in 3d in the Quake series of games. Id is taking a risk in alienating the fan base, true, but also I think it is a way to give something new to the Doom fans from those who started it all in the first place. Everyone has been dreaming of Doom's gameplay but with full 3d instead of sprites, dynamic lighting, openGL, and so on. Id can bring the next game into the works and introduce completely new technology while doing so within a familiar environment. With Quake 3's technology we have seen great game potential, and even greater potential in what lies beyond that.