They might very well have done so, however Apple was still using the 21.5" Retina / 219PPI display for the iMac even though LG had stopped selling it as an external monitor (in favor of the 23.7" 4K model, which is aimed at the MacBook and Mac Mini families).
That being said, Apple might consider 186PPI "good enough" for Retina now, especially on a lower-price iMac as these rumors claim (so Apple can still call it a "great display", even if it is not as great as the 21.5" display) while keeping the 27" iMac / iMac Pro at 5K and 219PPI.
That's an excellent point there - Apple is already stocking an LG display that isn't 219ppi and could be the 23" iMac display that has been described (because they would round down the panel size for description reasons) - the next iMac panel might have been staring us right in the face here.
If you take that at face value Apple would be breaking their own 'retina' rule that they've stuck with from 4k iMac 21.5" all the way up to 6k Pro Display XDR.
The LG UltraFine 23.7" is £629 in the Apple Store - not that much different in price than the 21.5" UltraFine was when it was on sale. It's also a lower resolution panel than the 21.5" - 3840x2160 (classic 4k) vs 4096x2304 (Full DCI P3 spec in the 21.5").
It's not the cheapest 4k panel out there but its IPS P3 wide colour gamut and 500cm/m2 brightness is easily better than the average 4k display. That monitor includes Thunderbolt ports and charging for 16 inch MacBook Pro (85w, not the full 95w) over the older display which only had USB-C ports.
Now, if Apple believe that this could form the basis of a replacement product for the 21.5" and quietly drop any claims of Retina display as long as the saved budget gets them full SSD then I'm with them on this.
A second half of the year launch could put them into Comet Lake S territory here but I'll still hang on to my idea of Apple consolidating parts with demand expected to fall by going with Comet Lake H (MacBook Pro 16") parts with mobile graphics cards like the AMD 5300M and 5500M - I note that the RX 5600M is out now.
Let me also add that I still get the feeling that Apple could still leave the existing 21.5" and 27" iMacs alone aside from a combination of adjusting the price, dropping models, or raiding the parts bin for upgrades - just like they did with the Mac mini.