One of my favourite series of all time. It takes the old sci-fi short story as a concept and applies it to a TV screen, with the same, amazing results. It is just what Sci-Fi is supposed to be, it gives plausible future scenarios to open our eyes to the dangers of the present. I'm glad that its audience grew, honestly; nobody listened to me when I suggested watching the first two seasons, but Netflix apparently has a lot more power than I do :D

Unfortunately, I still haven't been able to watch the latest season. I can't really comment on the new episodes. But I find your post very interesting, especially when you're talking about the future: the funny thing is, apparently you're worried that the technology we create will one day become our doom due to its becoming sentient, while I tend to be more worried when Black Mirror deals with our social problems and the changes in our way of seeing, interacting, judging others, judging the self....
I think that either way, on some level, we really don't know what the future will be about; we have always been somehow capable of fixing our screw-ups, but the sensation now is that we are indeed going too far. I just hope that this kind of sci-fi narrative will start having a tangible effect on our reality.