PoW = economics of scale and division of labor guarantee eventual centralization.
Not necessarily: a byproduct of mining is heat. It's hard to get rid of the heat in large centralized operations. In small operations less so, it may even be useful in some cases.
At some point mining cost will mostly be energy, not hardware. I've recently encountered a weird situation regarding solar electricity production (pretty decentralized in germany, where I live): in certain cases the array produces excess electricity which can neither be used locally nor fed into the grid for profit (due to stupid laws and regulations). Usually what is done in such cases is the electricity is just injected for free to the grid... what a waste economically, right? Well, if you have some cheap asics (so cheap that you can just have them laying around idle if not needed) you can make good use of the excess electricity.
What you are describing is a mis-pricing of investment/expenses. Just because a regular home miner severely undervalues his time invested in maintaining the equipment or the heat generated, those factors aren't immune to the economics of scale. Eventually the huge hot ASIC box gets thrown out because it barely breaks even while for the industrial miner a huge hot ASIC box is just a small expense line in one of 1000s running in a huge warehouse. Also there is no excess electricity. Either it is subsidized somehow ie someone else is footing the bill or again the cost is simply mis-priced by the miner and eventually that cost will come to the forefront and the small time miner will be pushed out by larger commercial players. You can't escape the benefits of division of labor.