There were original supposed to be 16
I don't think they were actually going to be 16 games, just 16 chapters. If Xenosaga couldn't make past 3 games, then why would Shenmue be able to. Shenmue was chapter 1 and Shenmue II was chapters 3,4, and 5. Chapter 2 apparently being the boat trip. I never played the games but I know this because I watched the retrospective on the series. Kikizo rumored in 2005 that all 16 chapters would be on one next gen console according to an article and released as Shenmue III. Unfortunately, Kikizo has their reputation ruined over this. Apparently, Shenmue III was in development but was halted.