One benefit of ASICs (and any specialized mining hardware) is that they decrease the threat of this problem. The marginal revenue for an ASIC miner is far higher than the marginal cost--most of the cost is upfront. ASIC miners won't turn their hardware off even if their profit falls precipitously.

On the other hand, anybody mining with a CPU, with marginal revenue close to marginal cost, will shut off the program as soon as revenue falls. This increases susceptibility to this failure as well as other attacks, especially by a 'terrorist' who begins mining at a loss in order to force all of the other miners into negative profit so he can monopolize the network.