How in the world would mineral oil cut your power consumption by half?!?!?  Its a heat transfer mechanism, not a power usage mechanism - except perhaps if your were, excuse me, but stupid enough to air condition your waste heat and recirculate the air.  The vast majority of farms just expel that waste heat.  Even if you recirculated, your air conditioning power usage would not be equal to your miner input power... and you would still need large fans to blow air through the oil radiator.  One way or another, that heat (equal to the power used by the miner) gets rejected to the outside environment.

That aside - from a macro economics perspective, profitability is VERY easy to predict:  Competition will drive it down until only the most efficient survive.  My single person 100+ mining farm has 3 costs to consider:  1) the cost of the building and land that it is on  2)  The cost of the equipment, and 3)  The cost of operating the equipment - which is just electricity since I don't draw a salary.  The first 2 are sunk cost, shy any expansion, which would just be a scaling issue.  Other operations have other issues (like rental of buildings, staff cost, etc.) to add to their electrical cost.  It is my hope that my average electrical cost will balance against their lower electrical cost plus their operating cost, at least for awhile.  Eventually it will not, and it won't matter if I have 100 or 1000 miners - once that balance tips, I'm out of business.  Good news for my competitors.  Others will likely fail before me, which is good news for me.  However note that difficulty just continues to increase, so people are not failing in sufficient numbers yet.