Isn't it so obvious that full-size desktop systems will always have higher potential than portable devices? Not only for audio, basically any purposes. Just think about the design constraints...
Nice portable setups may become more readily available in the future, but apparently desktop setups will be able to perform even better by that time.
Btw, as long as we're listening to music reproduction via sound-waves, I don't really see much game-changing improvement can be made to current situation. The ultimate solution should be something like block ear-hearing and listen to music at neuron level.
I'm really talking more about what the "perfect" end game would be for headphones, rather than talking about the pros and cons of where things are now.
I am not stating what is and isn't better today, I am talking about an end game. What is the perfect headphone, and the perfect gear for driving it?
If you had equal performance between a huge, multi-part desktop rig; and a small portable device that could also be plugged in at home - who chooses the former?
If you had two headphones that sounded equally good, one impossible to listen to with any background noise and needing a permanent, stationary rig to listen to; the other you could plug into a portable device and listen to on the train - who chooses the former?
If you had two headphones that sounded equally good, one so heavy it gives you a sore neck; the other light as a feather and you hardly know you're wearing it - who chooses the former?
We live with these inconveniences as enthusiasts because of sound quality gains. But if we could get dynamic, portable headphones sounding as good as the less convenient forms of technology, then those old forms no longer have any draw. If we could get small portable devices that sound as good as huge desktop rigs, then the old forms no longer have any draw.
That's what I mean when I say "the future". When convenience and sound quality no longer have to compete.
As for "how can things get better"... come on. Seriously?
There is not a single headphone on the market that sounds perfectly realistic. We don't even have that licked with headphones that are non-portable, open, and can only be driven properly by multi-thousand pound collections of heavy gear. Once we reach "perfect" sound quality (IF we do) then we have perfect functionality to contend with.