My first thought is - what will the modders do.

I watched some videos about MyHouse.wad (a Doom 2 level/mod that became popular with the indie horror crowd), and it's seriously impressive.

I wonder what happens in the context of Quake, after seeing the community take Doom to places Carmack could never have imagined.

I'm a lot more interested in how people mess with the rules of the game without necessarily breaking them, leading to some super subversive storytelling, rather than just porting the code onto a smart fridge or some shit.