After Apple had recently removed the monitors 
LG UltraFine 4K and 5K from its store, available there since the end of 2016, a successor is now listed, a 23.7" large 4K display from LG. The LG Ultrafine 4L display costs 749 Euros and has a resolution of 4K UltraHD (3,840 x 2,160 pixels), which is a deterioration compared to the predecessor model, which could still display real DCI 4K (4,096 x 2,304) natively - even more vertically.
Otherwise, the updated LG UltraFine 4K is slightly larger (23.7" instead of 21.5") than the old model. The color depth of the panel is as usual only 8-bit, the brightness now 500 nits - it's brighter than most monitors. The professional DCI-P3 color space is covered according to Apple.
The change from USB-C as primary interface represents an improvement - the new LG UltraFine 4K now has two Thunderbolt 3 ports, i.e. not only the computer can be connected to the monitor, but also a second display or a mass storage device in series. There are also three USB-C ports (with 5 Gbit/s). The Thunderbolt 3 provides 85W charging power, e.g. for a notebook.
LG UltraFine 4K
It is speculated that Apple will soon present a 6K (6,240 x 2,880) monitor with mini LED backlight, at least 31" in size, to meet the general trend towards larger displays and to be able to present both a higher contrast and a larger color range than before by means of local dimming. However, this will probably not be available until late summer.
Possibly also from own production, after Apple itself had left production in 2016 and presented the LG models in its store.
;)