For this to be applied, I think you need a steady network that would be able to record and store data be it offline or via an online storage.
With the above been said certain areas won't be able to support this feature as at now but its truly a nice project.
Yeah I actually just found out that they are trying to work together with Signal Messenger to try to always send the data through their chat. Which is an encrypted chat that was recommended by Edward Snowden himself so that might me a nice solution
Guess 2018 is going to be a blast, much anticipation ahead