Not to the satisfaction of current PC gamers. PC gamers are shifting to 120Hz monitors to reduce lag (the shorter the brain->hand->mouse->game->gpu->monitor->eye->brain feedback cycle, the better a gamer can react to changes in the game). Network play with current PCs would introduce at minimum two full frames of lag (one buffered on the PC after rendering, before compression; one buffered on the receiver during compression, before display).

I'd go out on a limb and say a majority of steam consumers are not the hardcore gamers you're talking about.