A crook (a dishonest person, especially a sharper, swindler, or thief) will mine using illegal free electricity. An honest miner will not.

In the short run honest miners will invest in new equipment that uses less and less W/GH/s. This will enable them to make a profit for a while. But it also means that older mining equipment will be useless. They will be sold at eBay for almost nothing. Say $50 for an antminer.

I imagine especially students who have access to un-metered electricity will pick up these. Even if one miner generates only $1/day, some cheap-ass eastern europens will run, say, three of these at no cost and cash in $1000 a year.