At that point, I’d still recommend something like cryptographed digital radio/mesh networks over internet-based messaging for most illicit organisation unless the infrastructure itself is held by the movement. Internet is too easy to disrupt, and smartphones are a security nightmare. Organising under the conditions of legality through apps is more okay, though.
But when the movement reaches such critical mass, forms of electronic communication will be necessary.
At that point, I’d still recommend something like cryptographed digital radio/mesh networks over internet-based messaging for most illicit organisation unless the infrastructure itself is held by the movement. Internet is too easy to disrupt, and smartphones are a security nightmare. Organising under the conditions of legality through apps is more okay, though.