Menial labor jobs could be completely eliminated within a 50 years. UBI might be a way to start that transition.
Construction, manufacturing, garbage collection, maintenance and similar are all on the chopping block. There is even talk of automation of many software development activities and high-knowledge professions like medicine and engineering. When I look at my role as a coder, data modelling, product design and requirements analysis are the only bits that I think might be very difficult for a non-sentient entity to do. Everything else could be done more efficiently by a machine. That's a probably 80% of today's jobs, gone or totally changed. The only activities that I don't anticipate being replaced are the truly human ones that harness our innate curiosity and creativity: art, music, law, research and exploration.
As a society we need to figure out how to keep the everyone engaged and interested in life. They need to be doing productive things or boredom will give rise to unrest and revolution will follow. The Romans knew this, "Bread and Circuses" kept their citizen populace occupied, while the menial labor tasks were 'automated' by slaves (who were treated as robotic minions essentially). We have the power to move the entire world population past the work required as part of the struggle to survive. What will they do next?
I think, we need to start transitioning to a cultural Renascence. A focus on art, music and creativity instead of work may very well be needed as the 'work' part is going to be hard to come by. If interplanetary and interstellar travel becomes viable, the focus could be on exploration and colonization. We need something to work at together to achieve, otherwise we will start to work against each other.