Is there not some sort of equilibrium for hash power? If difficulty is constantly reset so that only one block is mined approximately every 10 minutes and there is a 15 bitcoin reward for each block, all the hash power in the world would not RAISE the price. The price may raise the hash power, sure. But at some point the price of bitcoin will start to have a negative affect on hashrate.

For example, say $btc was trading at $50,000 a coin, the market would be so saturated with miners and mining pools that, for many miners, their computing time and electricity consumption would probably be better spent somewhere else as the odds of any one miner finding the correct hash and sealing the block should go down in tandem with hash power increasing.