2019. Jan. 15th
I found the news article that Hyundai MOBIS is developing the lamp which is able to communicate with users.
Original News article link here : http://news.hankyung.com/article/2019011573651

In CES 2019, at 9th Jan. Mirko Goets – the director of developing lamp in MOBIS – said that if there is no driver, the traditional method is meaningless. The role of lamp should be change for the Autonomous driving age . The lamp will be only door which can communicate externally.

Hyundai MOBIS is developing the lamp which is able to indicate the letters and symbols by the special display panel. It is preparing the technology to indicate the specific sign by this special lamp.

Director Goets is expecting that the role of lamp will be expand for Autonomous driving age and it would be main promising business for MOBIS for the future.

Here is the related article in English : https://www.cnet.com/roadshow/news/hyundai-mobis-self-driving-car-lighting-ces-2019/