And higher hashing power is more secure. The higher the hash rate the harder it is for anyone to pull off a coup of the blockchain.
This is not correct. If you hand mining over from a decentralized system of tens of thousands of GPU miners to one ASIC manufacturer it does not increase the network security.
For this reason we need to change the hashing algorithm from time-to-time, so that no ASIC can be produced (ASIC production takes a lot of time).
Honestly, it's just not worth it. In a few months, the same amount of time that it would take to find a new algorithm, if not longer, and implement it, Dash will be on Evolution. With Evolution, transactions will be approved by Masternode Quorums and the hash will only be used to randomly group these Masternodes into quorums. The miners will still include transactions into the blockchain, however, they will have no choice as to which transactions to include. They must only include locked transactions that passed a Masternode Quorum first. If they try to include anything else, it will be rejected by the Masternode network and the miner will lose the block.
It simply will become a new and infinitely more secure network soon enough. So please don't fret. Once this is in place, it won't matter if we only have one single miner.