Man, this is really the worst case we've been fearing in Germany as well, i.e. an overzealous government that wants access to the master decryption keys of any app using end-to-end encryption so they can backdoor them anytime they like. I really hope they have enough common sense left to reverse their course, and I have to say kudos to Apple for taking this fight.
Perhaps there is an app that makes using one-time pads simple. It is really the only way to be reasonably certain that your communication is protected. With storage so abundant it is feasible to share a 100MiB pad for each contact which should be enough for a lifetime of messages.
End to end encryption achieves the same thing without having to share large one time pads. The only people with your key are the people on the ends.