I'm looking forward to robotics a lot because solving menial tasks will have a huge class impact as we can stop looking for ways to keep a portion of society suppressed and dumb.
One can dream, right?
I don't like utopianism and I'm certainly not going to plan on a best case scenario. But I can't help a tiny fraction of my brain that says "There are ways in which it could turn out well." Probably not, but the existence of a best case scenario feels like it should mean something.
Also to pick up your conflict - when there are 2 possible outcomes you don't know yet - planning for the worst will have you lose either way, but planning for a good one (not best as this would mean to do nothing) leaves you with a positive chance.
So while it's true that the current jobs some people do will go away the total variety of jobs will continue to grow.
If you leave a working class citizen alone with a secure income he will educate himself or go with arts, we simply cheat him out of the possibility to discover his unique potential.