I see a couple of things here: first, the fundamental and philosophical question is what amount of time a person should work? History has set the benchmark by keeping people busy for about 40 hours a week but does that mean anything apart from people being occupied? It could also be 75% of that but instead focused on purposeful work without any clutter. Second, automation is not going to take sophisticated jobs that quickly - every statistical model (AI) is only using more parameters to approach reality - this is, in my opinion and from experience with corporations in their operations, not going to happen anytime soon. Third, The quest for purpose is endless as much as the ability for human creativity (as Einstein famously quoted), as a human race we are yet not aware of how much may lay in front of us - in particular I see space conquest as a domain for infinite potential. Remember, every new decade or age come with groundbreaking rules, norms, policies and structures. We may yet not understand them (why would anybody do x?) but we will make sense of it. Making sense of things in our environment is what consequently gives us purpose. Isn't that beautiful enough?