There's plenty wrong with Ethereum, but casting miners as 'the working class' is a flawed analogy. The mercantile class would be closer to the mark. Notably, their hashing power is based in real world economic power and they extract an annuity from capital expenditure on mining operations and hardware.

I also question whether miners are really providing the labour power, as you might expect the working class to do. They build the roads and keep the lights on but the means of production of value is (or ought to be) the services provided by those writing functionality that makes the network useful, i.e. the smart contract writers. Whether one thinks smart contracts on Ethereum have any value is another question but that was at least the vision.

A move to proof-of-stake does not remove the role of miners/validators. Validators will still earn a reward from validating blocks. So it's not as if this 'class' is being disenfranchised totally.

Finally the social class analogy entails disjointness of classes, this is certainly not the case for miners, many of whom are major token holders, and some of whom are involved in governance (of course by miners we are taking about the humans controlling the mining rigs not the computers themselves)