If I was going to setup a cartel play on bitcoin I would get a good hunk of the network hashpower together and then start squeezing tx fees.
Hmmm, there's a thought too, although I think the network will have to be a bit more transaction saturated before that will really work unless you have a massive percentage of the hashing power.
You're assuming that freshly mined BTC are the only BTC capable of being sold. There are already close to 11 million BTC in circulation, over 50% of the final number of BTC to be mined. Sitting on coins you mine would have a very small affect on the overall market.
Besides, this whole thread goes against the entire idea behind Bitcoin. It's a currency. It's meant to be traded and bought and sold and used to buy stuff. If everyone just sits on their coins waiting for the price to go up, then nothing even happens, and we all go home broke.
No, I'm only assuming that SOME of the BTC sold are mined, and reduction in mining output would reduce total supply by some fraction, but I'm not naive enough to think that it will be 1:1. The bandwagon effect would most likely be bigger than the miners restricted supply if it took off.
For example, if the open mining partnership decided that they would hold all but 20% of their coins (assuming that 20% covers electricity and operating costs for members, the numbers would have to be workable, these are just thrown out there), offer 20% of the held coins listed at a published price 10% above market (specific number, not fluctuating all the time, changing daily, weekly or monthly as the group desires), 10% of the coins listed at a published price 20% over market, and the final 50% in cold storage for the future. If this mining group controls 20% of coin production then the impact to the coin supply from mining then over the next period of time only 84% of the potential coins (3600*.84=3024 coins a day) and that would be without anyone else choosing to save their coins.
I am not saying this is the most awesome idea in the world, or that we should do it for sure, but I've seen this topic come up a few times and I'm wondering if we can come up with something that scratches the "cartel itch" that some folks have, but without the secret dealings and mob-like mentality. So, can we find something to scratch the itch without giving the cartel guys a knife to stab us with later?