I'd be hugely interested in this phone if only it had some form of cell connectivity; even 2G would suffice for my purposes. While we wait for cheaper 4G modems, why not a pluggable SIM800 (cost: a few bucks) module for the rest of us?
So far it looks like most people want 4G, even though it's quite expensive to add. I think too many marketing dollars have been spent convincing consumers that's what they need, so we may end up doing 4G before others. But you're right, 2G (or 3G) would both be cheaper and probably all you need for a dumb phone.
The nice thing, though, is unlike most phones it should be pretty easy for anyone with electronics skills to make a daughterboard that expands the phone hardware capabilities.