Shenmue 2 bombed so hard it put the series in a coma for almost two decades, and was also notoriously difficult to attempt to port (for technical and/or legal reasons; I know a 360 port was in the works but canned at some point.)
I kinda doubt Shenmue 3 will do that much damage, especially if Coffee Dog's prediction comes to pass and the launch is just Shenmue uber-fans lapping it up. I also have to think Deep Silver will try porting the game to anything under the sun that can run it, going into the future. We might see Shenmue Trilogy on PlayStation 5 or Switch 2, etc.
The series still has a future, it's just not particularly clear what it is yet. But at least there's hope, which I'm not sure you could say after Suzuki got "corner desk'd" and the Dreamcast died.