I would presume the quality of low-paying low-income jobs will increase. If people have the opportunity to leave there is an actual business incentive to treat employees well. I would presume the overall "quality" of the workforce would increase, as the detrimental effects of poverty on cognitive development and capacity is well known.

So who will do the dirty jobs? I presume ways are found in which to make them less distasteful. They are not about "dirtyness" per se, but about application of high dexterity manual labour on various tasks.