I think that Japanese companies are late in the game. OLED is quite a mature technology now, not like 2 years ago when the field was nor or less open. It will be quite challenging for them to snatch the market from Samsung, LG etc especially when OLED is mostly used in personal devices.
I was originally a skeptic of Japan Display Inc. (thinking along the same line as Wilber said that they are too late on it). But it turned out, the company apparently had done a remarkable job in combining expertise and knownledge of different display teams (which used to belong to different Japanese CE companies).
How Jpaan Display has succeeded thus far (against all odds) is sometihng to be examined, I think.