There’s a good chance physical humanoid robots will always be more expensive than humans, especially in this new hypothesised reality where there’s an enormous labour surplus.
The biggest practical issue will be that if these robots ever did start replacing people on a large enough scale, then you'd have a lot of angry, desperate people with a lot of time on their hands. So that alone will probably work as the primary mediating factor.
Quite an interesting time to be alive because the future is so completely impossible to predict. The world just a decade from now could look entirely different, or it could just be self driving cars all over again.