My best hope is that there will be some kind of OPEC cartel that agrees to limit production. The members could have unused reserves of mining hardware that ramps up when somebody violates the agreement.
Those limits were baked into the design from the start. In the current design there are only 21 million Bitcoins that can be mined, and we're approximately 80% of the way to that target.
http://www.bitcoinblockhalf.com/
Also, Bitcoin is designed to be harder to come by as time goes on. The number of new coins issued diminishes over time. See the Supply Growth section here:
https://en.wikipedia.org/wiki/Bitcoin
"12.5 bitcoins per block (approximately every ten minutes) until mid 2020, and then afterwards 6.25 bitcoins per block for 4 years until next halving. This halving continues until 2110–40, when 21 million bitcoins will have been issued."
There will come a time when Bitcoin mining is no longer profitable. If the scaling problems with the transactions are solved in time, we may see more people trading in Satoshis (fractions of a Bitcoin). The scaling problems are pretty hard to solve though, it's probably going to take a hard fork to make Bitcoin a true alternative to traditional government-backed currencies.
https://en.bitcoin.it/wiki/Difficulty#What_network_hash_rate...
Won't work. If a mining cartel agrees to keep difficulty and hashrate low, they're just making it easier for those outside the cartel to mine more Bitcoin.
Cartels usually don't last forever, but they can last for a while. In the case of bitcoin, it could reduce total energy consumption.
Exactly. This is similar to how price dumping works: https://en.wikipedia.org/wiki/Dumping_(pricing_policy)