It's not that convoluted, it's definitely easier to grasp when you were brought up on a diet of low budget but high concept television where the surface details were always second place to the narrative content.
As I posted earlier there is clear torch passing between each film (well at least for the first three), they are meant to be part of the same narrative but always set 'any minute now".
Television shows like The Changes and Survivors are also set in the near future but made in the early seventies.
When watching it now I have to turn a blind eye to the surface details from the decade that taste forgot and imagine it happening sometime very soon.
That is at least the way I see them and if you want to see them in another way I can see how but I'm not persuaded to change my own interpretation.