Sad, but not surprising to see Apple discontinue the Pro Display XDR. Hard to go back to 5K once you’ve used 6K.
The pixel density is the same I believe - I guess their theory is that 5K is more fungible than a large 6K display since people looking for more real estate can daisy chain the 5K displays.
Same pixel density, but smaller monitor though.
I vaguely recall an Apple rumor from the last few months about 3 new display model numbers, 2 of them being 27" and one of them being 32"... so still possible a Pro Display XDR refresh is on the horizon.