I think its easy to scare yourself with what might happen. A total comms / navaid failure requires an alternator failure, then fully discharging the battery. Not all that likely.
But it has happened and Sod's law ensures it will be in IMC. It took one hidden circuit breaker (no decal, either to indicate the position of the circuit breaker) to be inadvertently jagged. Loss of all electrics and the battery of course. Night in cloud en route West Sale to Essendon. Loss of all comms and navaids and of course Sod's law prevailed again when the gear was inoperative due no electrics. No flaps or landing lights and no cockpit lights. Again Sod's law hit hard when the emergency landing gear handle was found to be jammed and inoperative.