OLED display has some advantages over LCD, like high contrast level and deep black color. But in terms of pixel density, there are many LCD panels with extremely high pixel density. Otherwise there are only a few OLED displays with high pixel density, like Galaxy Nexus (316 ppi pixel density) and Galaxy S III (306 ppi pixel density). However almost all display with over 300 ppi pixel density uses LCD technology.
New Samsung’s components most likely can be used to make OLED display with extremely high pixel density up to 350 ppi. As an illustration, a 4.2-inch HD display has a pixel density of 350 ppi. With Fine Metal Mask technology, Samsung can produce high pixel density displays without a lot of troubles. That gives a hope for the current biggest smartphone manfacturer to apply it on commercial devices.