Without light.
Without food.
Without a future.
What systemic failures led to the collapse of the Soviet Union and the Warsaw Pact? That is the only instance that I can remember of a communist totalitarian system collapsing.
As long as the Cuban Government is able to inflict terror and fear among the people, they will have the ability to remain in power.
Mao and Stalin were able to starve millions and still remain in power.
The Venezuelan dictatorship is still in power, with a new dictator.
The Lenninist-Stalinist-Maoist totalitarian communist systems are structured to treat their own populace as their greatest existential threat, and to disarm them of weapons, thought, and spirit.
As long the Cuban Government can oppress and repress its own people, it will remain in power with or without electricity.
Like Iran and North Korea, they will make use of organized crime to obtain many of the things they are forbidden by the outside world.
It will be the Cuban Government's failure to keep its party elites in the lifestyles to which they have become accustomed that will bring about its collapse from within.
The Cuban Regime does not need to provide for all its people to survive, it only needs to continue to provide for the party elites - those whom are more equal than others.
The only infrastructure the Cuban Regime truly needs is the infrastructure of fear and terror.