Oh wow, I hadn't even thought of m.2 but you're spot-on. There's a ton of space in there, and we know the SoC has PCIe lanes.

Welp, who's gonna solder one up first?

I wonder what signals are on the J5 connector...

You're spot on - a touch pad integrated into the case would mean you didn't need a separate mouse; there's plenty space for an M.2 module, and SD cards are shit; and mini-HDMI really is such a pointless form factor.

I'd be ordering one of these tomorrow if it had these features - still, I expect it will sell very well as-is, so I'm really hoping they come out with a new version at some point!