I'll also jump into the team that thinks Shenmue IV will happen, and will be the last one.
At the circumstances of Shenmue III conception, with all the power of the comeback and the record-setting kickstarter, it was sensible to think the series had a chance for revival, and thus the hope of unfolding the story slowly. But at this time of conception for Shenmue IV, almost all of that has disappeared. And it will probably come at a later date than if III had been a big success. And Yu Suzuki has a somewhat advanced age.
In addition, I think its completely viable to wrap up most of the story in only one game. Remember that the original Saturn concept was of a much straightforward non-open game. Or the minimum $2 million Kickstarter possibility. Remember that Yu Suzuki hasn't been afraid of making drastic cuts and reworks of the original 11-chapter plot. And remember that Yu Suzuki's mindset this time around is not being faithful to the core Shenmue formula "for the fans", but rather mixing up the concepts to attract newcomers. All that could perfectly lead into an story-heavy, much less open game.
I can envision a Shenmue IV with only three locations:
- The cliff temple/Baisha, because it's where it has to pick up after 3, and where most of the Chiyoumen plot could be resolved: the 4 leaders, Ziming, the civil war, etc. They possibly have some assets ready from Shenmue III development.
- Luoyang: where Shenhua's lineage and role would be resolved. Maybe the treasure could be placed here too.
- Meng Cun: where the mystery of Iwao and Zhao's murder would be resolved, and Ryo could find closure (and possibly Lan Di too).
They could reuse Bailu's assets from Shenmue III for an epilogue of sorts, if they want, too.
The rest of the chapters main elements could probably be scrapped, or reworked between the rest.