Bitcoin Mining Difficulty Attack

I can't seem to find much online about a type of mining attack on bitcoin and want to know if anybody else has played out the game theory on this.

The attack is done by raising the mining difficulty then turning off all the hash rate that the attacker used to raise the difficulty. While all friendly miners continue to mine they will require to use more electricity to find the blocks until the difficulty adjusts back down, also increasing time between blocks. Once the adjustment is complete the attacker switches their hash rate back on and block time reduces, earning the attacker more bitcoin in a shorter space of time for less electricity.

If enough of the hash rate is controlled this way it could cause major disruption to the bitcoin network, as the cost to attack is not in electricity+hash rate, but just the capital to have it sitting dormant while they wait for the adjustment.

We can see the hash rate increasing and as happens with a lot of industries I can se a future where we have just a couple of huge companies owning the majority of the hash rate.