Already can do 8 but as someone mentioned it is a shame that the PCIe 3.0 drops to a single lane for what I can see as an addition of a 1gbe.
I will have a punt about the Serdes lanes so that you can correct me and explain properly to the community. 
The RK3568 has 2x Serdes buses a 2 lane 8Ghz one connected to PCIe and a 2 lane 5Ghz that is a really confusing collection because it can be muxed into so many combinations.
Cnxsoft gives a usual good review of capabilities https://www.cnx-software.com/2020/12/01/rockchip-rk3568-processor-to-power-edge-computing-and-nvr-applications/
As so far there has been no mention of the Quad serial gigabit media-independent interface that can provide 5Gbe
The RK3568 depending on chosen mux pattern and connectors can be a whole range of devices and what I think is missing here is the CM3 SoM as that for me will be the perfect industrial board.
Maybe a few choice carrier boards of specific focus will be provide or like Raspberry a all-in Dev board and the carrier and function will be down to customer design.
Its not a matter of more boards as currently x8 Sata could be supported and +2 is not much of addition, but its biggest problem is bandwidth as your juggling with the bandwidth of the Sata controller and the access of the Network provided.
Its a no brainer that the unique selling point is NVR/NAS as the RK3568 has been designed with some quite unique NVR/NAS features.
The camera interfaces + NPU + recording makes for some cutting edge NVR that probably could also make a descent application NAS.
Because of the forum I know that a CM3 based on this is likely and due to that I now think you already have too many boards.
The Rock3A I presume is designed to work with the same sata board that RockPi4 does but double bandwidth.
The Rock3B due to dual ethernet with failover I presume is trying to focus on ‘more’ industrial applications.
But because a CM3 SoM is imminent and likely to provide a whole range of industrial applications you have a Rock3A with the same form factor of the RockPi4 so likely it can use the same PCIe adaptor board.
I hated with a passion the PCIe connector and how it mounted on the heatsink that eventually got fixed to some extent with a proper shielded PCIe extension cable.
Why on a new board you are copying what turned out to be sort of OK when you can just use a m.2 JMB585 direct even if the Penta Sata Hat was a good price, as it already exists for the RockPi4 and m.2 JMB585 cards already exist.
The Rock3b provides a great format but then loses a lane for a concession to be more ‘industrial’ whilst really that is likely to be the CM3.
You probably have too many boards already with fractional amounts of difference and for me a 2 lane Rock3B with singular but maybe faster Gbe?, no Rock3A and CM3 give difference and choice to the RockPi4 as why provide an almost identical board.
I think the bluetooth/wifi on PCIe m.2 E key is a good idea as it gives choice if needed or even LoRa or other E key cards, nRF52840.
The keys on M.2 cards confuse but are A + E keys just like B+M where they will fit a A or E keyed connector.
As presume a A+E key Nic could also be used or even M.2 E key Accelerator with Dual Edge TPU with multiple accelerators?
