What year of AD we’re now?
The more people mining the more electricity people are spending overall; such people need to recover costs of rigs, rent, and power. This sets a minimum price accepted by a consistent participant in the market: the miner.
The more people mining the more rigs you need to stay competitive the higher the overall cost, the bigger price you will demand for the Safex Cash.
Then on the more philosophical point. If we dont have enough diverse mining, then we become susceptible to a 51% attack.
It’s good for any network to have as many miners as possible to prevent 51% attack
ETH will release hybrid version first, with mixed POW and POS. They will implement the difficulty time bomb which will increase the mining difficulty exponentially until the chain becomes impossible to mine, and enter a so called ETH Ice Age. No fixed date yet, but hybrid version should happen in 2018. The transition to full PoW will be slow, but miners may already want to start looking for more profitable coins to mine, such as Safex Cash.