Even if fees are about the same as today, it still would make sense to run ASICs in for many other uses. For example, many hobbyists tinkerers use asic miners to heat their homes, greenhouses, or even hot tubs.

In a world without a block subsidy, I find it hard to imagine that large warehouses pulling 12+ MW to mine BTC will still be profitable. Instead, I imagine that asics will become integrated into common household and industrial appliances.