Neither Smooth or I agree with AnonymintTPTB_need_war (aka sockpuppet1) about BTC mining having a predictable endgame. It's entirely plausible that commoditization of sha256d could make most big mining farms extinct, with the only miners remaining being people that use the waste heat to power some other type of utility: water heaters, central heating, industrial use, etc.
I destroyed this logic fail from smooth in the past. Did you miss it?
Electricity is nearly an order-of-magnitude less efficient way to create heat. No one is going to compete with nearly free electricity in China (due to corruption) by paying more to heat their homes.
Even if Chinese mining farms were not getting political favors in exchange for promising to follow the government's edicts on regulation of mining (which of course they will do as any rational person will do because if they don't someone else will avail of the offer from the government and of course the government of China wants to control Bitcoin, duh!), it would still be the case that Chinese mining farms will always have greater economies-of-scale which will make it impossible to compete with them by getting part of the electricity for heating your home for free, because again you could heat your home in much more efficient ways especially factoring in the capital cost of the latest generation competitive ASIC mining equipment, as compared to for example adding better insulation to your walls or double paned windows, etc..
I think you are wrong about this, but only to the extent that current huge subsidies in various forms (I'm including likely corruption) in China become less significant, and also probably assuming ASIC commoditization.*
Eventually you get to a point where even though the waste heat is worth less than the electricity that goes in (as your comments correctly state), using it still adds to you efficiency and not using it will be uncompetitive.
* You and I both view ASIC commoditization is significantly less likely in the foreseeable future than r0ach believes. I may differ from you in that I don't completely rule it out longer term.