Yes, robots (or thinking machines) will replace lower classes. Labour and menial precise production will become none existant, I`d say within 60 years. And after that, when we merge with our technology (the actual word being synonymous to us), what we would consider today to be robots, will replace such things as art and literature (we will see evidence of that sooner than we will see a replacement of all menial labour).
I don`t think we`ll become communists. When machines take over work, who gets the benefits? We will most likely become entrepreneurs, dynamic and insightful thinking will be rewarded and so will push the Law of Accerated Returns to its max (not really, but you get the idea).
A society of idle rich is before us, where there will be more leisure time (we can already compare today`s from 50 years ago, it`s enormous) and I believe we will pursue such activities as learning (it will be required to learn new skills constantly if you are to hold any intellectual position, which almost everyone in the First Worlds will hold) and getting `back to nature`(hopefully we still have one to get back to).
Yes, we will create a perfect world. How do I know this, because we will have to ability to create our own.