I'm still surprised Yu Suzuki decided not to finish the series with this game and instead leave it unfinished when it took this long. To me, it's just such a slap in the face to diehard fans. At this point, I think there is close to zero chance that Shenmue gets another sequel. Shenmue 3 likely wiped out its goodwill from those with some curiousity, leaving now only a niche of a niche to support a fourth outing. This franchise is dead.
It was known from the start of the Kickstarter campaign that Shenmue 3 would not finish the story. Yu Suzuki said that there would be 11 Chapters and would require 4 or 5 games to tell the whole story.
Following the Kickstarter comments since the start of the campaign, I would say that more backers were upset about the Epic exclusivity and botched campaign rewards during the launch window.
I played the original Shenmue on my Dreamcast , imported Shenmue 2 for Dreamcast to play it early, then replayed Shenmue 2 on Xbox. Recently I replayed Shenmue 1 and 2 on my Xbox and PS4. I'm a diehard as well, however I do not feel that the story should have been completed during the 3rd outing, it was never an expectation.
As I said before, Y's Net has financial backing from Deep Silver. I do believe that there will be additional Shenmue games in the future. No doubt that they will get additional funding from Epic if they continue with another store exclusive launch for PC. In my opinion there probably won't even be another Kickstarter.
Shenmue was always a niche of a niche game. It isn't dead just yet.