Well, look at the Audeze or Hifiman... They release their flagship model almost every year and even though they still havent beaten HD800 (trying to do so for years), people praise them for bringing HUGE IMPROVEMENTS each time.
In other words, LCD-2 were supposed to be better than HD800... Then LCD-3, now LCD-X... The same goes for Hifiman... And yet all their headphones are still on the level of the HD800, at best. Do you see the trend of diminishing returns more clearly now? I do, as well as Tyll from Innerfidelity :-)
Is the LCD2 r2 better than the HD800?
Comfort: LCD < HD800
Detail: LCD < HD800
Reference Neutrality: LCD < HD800
Bass Resolution: LCD > HD800
Fun Factor: LCD > HD800
Scalability: LCD < HD800