Since the mainboard is pretty long in the tooth there’s plenty of room for improvement.
- USB-C data.
- Switch the CM3 slot for CM4 (this would break a lot of mods but would give CPi the most flexibility).
- Remove the WLAN from the mainboard as it’s only used for CM3-native modules.
- Easy: Internal SD card slot, put the external slot on USB. Hard: Mainboard NVMe.
- USB 3 on the CM5.
- Stop using DSI-0 entirely; drive the screen via HDMI somehow and make mainline useable (bonus: this makes UEFI useable).
- Fix the screen backlight flashing on startup.
- Make the mainboard work at lower voltages to fully use 18650s.
Of course I personally would much rather the CM3 slot stay so I can keep using my lovely HackerGadgets mods, but if it had NVMe I might trade them away…