Considering their whole electrical system been hanging by a thread for decades now, I would wager it's absolutely possible in the near future that it one day fully dies if nothing is done about it, however for now it seems like it's slowly going back to its stable instability, usually they will have a few hours of electricity a day/
I've been looking into the problem and since I regularly watch a podcast from a very close source into the status of Cuba right now (El Ático de Pepe Forte) I can tell you that it's back to "normal" at the moment.
It lasted 4 days though. No electricity at all for 4 full days, and some areas still in the dark, just gaining back access little by little.