ian, you are looking at the evidence in front of you. I respect that.
However, part of my participation on this forum means that I am exposed to this topic a lot - and therefor aware of other comments made by the ZorinGroup here and on other media like Twitter. They have addressed this question in interviews as well - and have stated it is their High Priority Item.
The ZorinGroup have addressed this quite a bit:
As readers can see, the ZorinGroup have directly stated that they hope to release a Direct Upgrade path without need for Reinstall in the period between the release of Zorin OS 16 and the release of Zorin OS 17.
This includes Zorin Pro, as well as all editions of Zorin OS. So it includes Core, Lite, Education...
On the Main Zorin OS page, this is also covered:
In the meantime, we recommend that you use Zorin OS 16, which will be supported with software updates and security patches until April 2025. You will also be able to directly upgrade from Zorin OS 16 to 17 shortly after its release.