again, it's the marketing machine speaking here...
Your (and definitely mine too) eyes aren't going to improve in the next 2.5 years.
Max brightness and color accuracy are the most important parameters by far, and they already are top notch on the iPhone. The only way to improve the display is to raise the resolution, with marginal gain maintaining the current display size of 4.7".
Yes, they could do that and obtain an higher PPI, above 400PPI, but it would be mostly a marketing gimmick.
Ok, I give up.
You' ll always want the last word.
No marketing bs.
It is very good now, I get it. But the way you are saying it, it will never have to improve.
It is good now, so why improve it?
They could even use this same screen in the iPhone 10.
Our eyes are not going to improve.
My eyes will go worse over time.
So Apple can even put in a worse screen.
I won' t notice. Good for their margins.
But seriously, there are already better ips lcd screens out there:
For instance the new lg G5 screen is rated at 900+ nits.
The nexus 5x has better color accuracy and better blacks, better greyscale accuracy, etc.
Just look at the anandtech review.
And you forgot mentioning black levels. iPhone 6/s black levels are not in the lead there, about in the middle of the heap.
It is good now, but in the next 1.5 years, this lcd will pale by comparison with the competition.