This is apparently due to Apple’s potential use of new display tech from Samsung. Right now the display works by having touch panels layered on top of the OLED/LCD panel. However Samsung has developed their own technology called Y-OCTA (Youm On-Cell Touch AMOLED) that integrates the touch sensor into the display panel itself, thus eliminating that extra layer.
The report from Korea claims that Apple and Samsung have signed an agreement in which it will see that tech find its way into 2019’s iPhones. It has also been reported that the tech is 30% cheaper than the standard tech, although we don’t think that Apple will reduce their iPhone prices as a result of that.
That being said, it is unclear as to how much thinner the iPhone could get by removing this extra layer, so how big of an impact this might have on the overall thickness and weight of the iPhone is anyone’s guess for now, but this also means that Samsung will continue supplying OLEDs to Apple for the foreseeable future.