[heurist]

Happiness can be induced chemically. I imagine future societies will have clean drugs to enable safe perpetual happiness in an existence where humans are to machines as dogs are to humans, humans don't have to labor for resources, and existential depression is the main cause of death.

I don't think people look out far enough when projecting the future. Or maybe I look too far out.

[civilian]

> I imagine future societies will have clean drugs to enable safe perpetual happiness

I was going to argue this point, but you solved later in the sentence: " and existential depression is the main cause of death."

The easiest way to resolve this inconsistency is that there are multiple kinds of happiness. I like this description: http://sensophy.com/the-holy-trinity-of-happiness/ Happinesses are Pleasant, Good and/or Meaningful. Your imagined future wouldn't contain anything meaningful.

[kazagistar]

Meaningful might be a finite resource.