So, you seem to be saying that in a world where all our digital comms (email, SMS, devices, storage, etc) go dark, law enforcement will simply be forced to come up with/adopt even more intrusive surveillance tech to overcome those obstacles. On that, I agree.
Nevertheless, I don’t think the legal obstacles here are that big. CALEA simply required all telco providers to upgrade their systems (sometimes at multi-million-dollar costs) to ensure timely, prompt access by law enforcement in the presence of a valid warrant. Congress could do the same with Apple, Google and Facebook: protect your systems, but you have to allow us access when we need it. Otherwise, you can’t offer your services in our jurisdiction. It’s pretty straightforward.