First of all: there is no such rumor - just my hopes and overactive imagination and the following factors:
- Assumption: The upcoming Z 9 will be positioned at a price point similar to flagship bodies such as the D5, D6, Sony A9, and modest used automobiles
- Fact: The D500 was the crop sensor solution that brought D5 technology to a price point accessible to a broader market.
- Assumption: The Z 9 will AF with the speed, precision, and reliability to satisfy D5/D6 users with Eye AF that improves upon existing Z 6 II and Z 7 II capabilities.
- Fact: While not as good as the D5 (which I don't own), the D500 consistently outperforms the Z bodies in AF
- Assumption: Nikon, if they follow their existing playbook, will release a crop sensor version of the Z 9 (presumably called the Z 90) not too long after the Z 9.