Reports from Korea say that Samsung is talking about using an LCD display in the upcoming Galaxy S5 and Galaxy Note 4 mobile phones - mostly in an attempt to reduce costs. Samsung is facing competition from lower-cost Android phones and need to lower the cost of their phones.
Samsung started adopting AMOLED displays in their high-end mobile phones years ago, but whenever people start discussing the next one, there are always rumors that they will switch back to LCD. It happened with the Note 3 and with the GS4. As we know, both phones use Super AMOLED panels.
Samsung repeatedly said that the future of high-end displays is OLED. Just last month, during Samsung's Analyst-Day, it was made clear that Samsung will continue to adopt OLED displays, and in fact they are gearing up to start adopting flexible panels (which Samsung estimates will reach 40% penetration in mobile phones by 2018).
However, we do know that currently AMOLEDs are more expensive than LCD (a large 5" AMOLED costs about 25% more than a comparable LCD) and it is expected that SDC will face supply issues soon as their OLED capacity will not be able to meet demand. So I guess Samsung will continue to offer several different phone models, and some will indeed adopt LCD. For example the GS4 Active uses a 5" Full-HD LCD. Hopefully there will also be a GS5 variant with a flexible OLED.