The two board approach is interesting but seems really impractical. It seems like you'd want to upgrade the $6 base board (i.e. USB 2 to USB 3) as often as you would the $20 module. Storage would make more sense on the baseboard to me to make the module something you can easily swap to upgrade compute without copying data around. Or if storage were a separate m.2 but then we're just reinventing PCs in yet another form factor.
Proprietary nature of course ruins the concept because no way this company sticks with it more than a couple generations. If it were an open standard it would be a lot more captivating.