Illusions. When we didn't need 80% of people farming new jobs came along. When we didn't need a big chunk of the population working in factories service industries and computers came along. Something else will come along, again this is all based on what has happened in the past historically.
What will the new jobs be like? Well hard to determine. I suspect there will always be the need for human interaction in the service industries. Possibly WAY in the future we will have robots life like and with personality but that is still Sci-Fi for now.
Maybe there will be a bigger need for robot repair men or robot programmers. Maybe new technology (like the computer did in the last 50 years) will open up new jobs that we haven't dreamed of having before.
But taking a look from your point of view are you suggesting we shouldn't have robots because they might replace too many workers?