I’d like to see an open source foundation that designs 3D printable tablet cases, and publishes the files, along with instructions for building open source tablets based off of single board computers (ie Raspberry Pi, Pine, etc) and available existing components (ie touch screens, batteries, etc)—similar to what Zynthian.org has done for musical devices.
BLE has a very short communication distance (absolute max range 100m in laboratory conditions). This would make it nearly useless unless you and the person you are communicating with are in the same room—unless EVERYONE used the app to allow mesh communication. Either way, it seems to impractical for it to catch on, sadly.