It hurts short term. This means the fees for Bitcoin transactions increase. If not by the old mining power coming back online, it will be solved either by the

It hurts short term. This means the fees for Bitcoin transactions increase. If not by the old mining power coming back online, it will be solved either by the next difficulty change, after which the Bitcoin network will again operate at full speed but using less energy, or by market powers if there are miners standing by due to not being profitable, which they now may be due to fewer miners to share the rewards with.