This is completely wrong. The cost includes mainly the hardware cost. Once you have the hardware, turning it off is the most idiotic thing a miner could do. So scratch that conclusion from your mind 
Miners might stop selling if the price goes too low because they need to get back invested dollars, that is the only thing that would happen with (theoretic) low prices. Current price of bitcoin to make asic mining not profitable electricity-wise is about 30$.
You other ideas about bankers taking control over bitcoin etc were also fun to discuss in 2010. Now, there is no such danger, we moved to a higher level, government regulation level. Once bitcoin takes another baby step, that won't be a problem as well, because it will move to a completely distributed acquiring network by 2015.
Miners might stop selling if the price goes too low because they need to get back invested dollars, that is the only thing that would happen with (theoretic) low prices. Current price of bitcoin to make asic mining not profitable electricity-wise is about 30$.You other ideas about bankers taking control over bitcoin etc were also fun to discuss in 2010. Now, there is no such danger, we moved to a higher level, government regulation level. Once bitcoin takes another baby step, that won't be a problem as well, because it will move to a completely distributed acquiring network by 2015.
Can't argue with your point regarding miners as I don't know enough about it.
Regarding bankers/financial pirates not taking over Bitcoin, With a market cap of around $6 Billion, Bitcoin is still very much a penny stock in the grander scheme of things. Any establishment financial house could grab as much of it as they wanted at any price that they wanted. If they were to take an interest in it however, the most likely price that they took the lino share of their stake in Bitcoin would be at a very very low price and they have both the expertise and the funds to ensure that the market was depressed low enough as to be to their liking. This sort of thing goes on in the finance world all the time. I find it amusing that you somehow think that Bitcoin is immune.
If any government really wanted to destroy Bitcoin, they could crash the price to single digits for the price of a few dozen cruise missiles.
Bitcoin is not going to 'beat the bankers'. Not ever.