2007 it was Crysis:

"This is a game that's so complex it not only pushes the latest PC hardware to its limits, but it will tax the next generation as well. It's so huge and ambitious that it's pretty much impossible to replicate the entire Crysis experience on a console without making significant compromises. But by making such a cutting-edge game, Crytek has not only given us an experience that showcases the power of today's PCs, but it has also offered a glimpse of tomorrow."

But who could have guessed that "tomorrow" meant MGS4...