We're likely approaching the day when it'll be more cheap to attempt to build an open Linux phone from scratch rather than keep waiting for a manufacturer to listen to a few thousand techies who don't want their personal data chewed by proprietary OSes. That milestone will almost certainly be marked by the availability of cheap 3/4G modems (I'd be perfectly fine with 3G if it was the only option). We're not there but chipsets are becoming cheaper with every portable router or dongle sold, so it's a matter of time. Cheap and small SBCs, displays, batteries and 3D printed cases are already here waiting for the 3/4G chipset to be added.