Here are my theories for Shenmue III
1.)Lan Di=Dragon and Ryo=North Star?
In the bad ending of Shenmue II, Shenhua told Ryo to hurry while the dragon clouds Ryo with black surroundings. And when Lan Di shows up and kills Ryo, She said the dragon called the clouds to hide the morning star; so Lan di must be the dragon, and Ryo must be the north star. Perhaps it just a prophecy. I'm not sure if this one's correct, But we will find out in the next game.
2.)Glowing lights on the center of each mirror.
We knew that the mirrors were made from the Phantom River Stone in the Guilin Region. But about the glowing objects on these two, I will give you 4 examples. Here is the first example, After Ryo left the basement, when Ryo carefully observes this mirror while Fukuhara felt creeped out when he thought Ryo was possessed by it. Then for a next example, While discussing Yamagashi about the mirrors, He said that these mirrors contain the treasure of good and evil, like the yin and yang. It means that he has to be careful that has something to do with his father's death. A third example, like my last theory, before Lan Di kills Ryo and snatches the phoenix mirror, The glowing object of the phoenix mirror stops glowing red. But in Shenmue I, the dragon mirror keeps glowing green when Lan Di possesses. And the last example when the stones that Shenhua's adopted father got, Shenhua declared that these stones contain voices. Like the second example, maybe these glowing lights have the same similarities like the stone.
3.) Sunming Zhao
In an interview with Yu and his one of his ideas for Shenmue III, we learned that the man with Iwao in the photo, could be Sunming Zhao. We knew that Zhao was killed in Meng Cun, but Yu stated that he will play an important role in the next game. Perhaps he is the adopted father of Shenhua, and maybe he has a different name to hide from enemies, just like Obi Wan changed his name to Ben Kenobi from Stormtroopers in ANH.
4.) Phoneix and Dragon mirrors
In Shenmue I, Master Chen told Ryo that if the mirrors are formed together, the chi you will resurrect itself and devour the world. But in Shenmue II, Yuanda Zhu said if the mirrors form a key, the treasures will be found to revive the Qing Dynasty. Although We though Zhu contradicts himself about the mirrors, but perhaps for the chi you men, they are doing it for evil; And perhaps he probably didn't know about using the mirrors for good, after he Told Chen about the mirrors. Until when he studied to find if there is another way to use the mirrors for good, while being hidden form the chi you men.