When this happened during the Arab Spring, people did things like using dialup to other countries and setting up public WiFi.
In Belarus it seems the shutdown wasn't total and e.g. Telegram worked better than many other services.gizmodo.com/belarus-turned-off…
What it sounds like @delta
is talking about above is attacks targeted at certain networks, and of course those won't affect people who are on an alternative network, especially one that lacks a central chokepoint.