As of right now, we know with some certainty that Shenmue III won't end the series, and that we'll likely see its conclusion in a fourth game. In a typical trilogy, the second installment is when the protagonist(s) is at their lowest point, aka- when all of the "bad stuff" happens. Two perfect examples of this are Star Wars: The Empire Strikes Back and The Lord of the Rings: The Two Towers. In both of these scenarios, even the title has a bad connotation. Within these particular films, the main characters reach their lowest points, whether it be desperation, depression, fear, anger, etc. Obviously this didn't happen in Shenmue II, so I expect to see it in III.
What are your predictions? Any more deaths? An attitude change from Ryo? A betrayal? I imagine Ryo will have a near-death experience as a result of the Chi You Men, similar to Luke Skywalker's encounter with Darth Vader.