The best headphones at/around the $1000 is the pair you get for half the price.
I've been very happy with two recent purchases, one on a massive sale and the other used. Both discontinued. The Focal Elegia and the Audioquest Nightowls. I can't call either of them the "best" around $1,000 (original MSRP was like $900 and $700 respectively)...but I'm also not sure if there is a "best" really. Diminishing returns concept aside, I think really the goal is finding the sound signature that's most pleasing to you (and this can vary depending on the genre of music you're listening to). In other words, it's highly subjective after a certain threshold and I'm not sure that's $1,000. I think that's more of a reflection of supply/demand and what the market will bear. A little bit of conditioning and marketing too.
So in my case, I'm talking about discontinued headphones. Does that mean they aren't at/around the $1,000 mark? (yes arguably the Nightowls weren't ever at that level, but the Elegia were and it's direct replacement is now even more expensive and the Celestee has mixed reviews on being "better" than the Elegia). What changes in a few years? The headphones? Or our perception of value? Or did we just grow bored of a headphone?