...and speakers will never be headphones, either. My wallet is grateful for that. (Also, holy crap, thread bump...)
Well, perfect 3D sound is my goal because it's about "being there", and also about getting a competitive situational awareness advantage. I miss the days when Aureal was still around to heavily push proper binaural 3D sound in games with A3D. They could get some of the effect through speakers, but it requires crosstalk cancellation and other trickery that headphones don't need, so it worked a lot better on headphones, as HRTF-based mixes tend to in general.
And when it comes down to a good binaural HRTF mix, it's blown away every 5.1 and 7.1 speaker system I've listened to when it comes to exact positioning, especially paired with the right headphones (like my trusty Stax SR-Lambda). Why, then, would I want my headphones to emulate speakers? I can have something far better than that, something so accurate that I can shoot a guy through a wall just by listening to his footsteps! Or I would, if the AAA game development industry decided that 7.1 speakers worth of audio were all we needed...clearly, they don't know what they're missing.
Yes, I'm clearly coming from a different angle than most of you, who are looking at music...mastered with stereo speakers in mind, not headphones. Strangely, such sources don't bother me when played through conventional stereo headphones, even if that's not what the mixing engineers had in mind.
Ideally, everything would be recorded in ambisonic format with a soundfield microphone, and we'd have a recording that can easily be tailored to speaker and headphone listening alike, without being forced into a fixed HRTF like a binaural recording...but I don't see that happening for a very long while, if ever.