Satoshi thought and planned for it.
If the bitcoin price falls below the cost of mining, some miners will exit. It will temporarily cause block discovery to lengthen as the existing miners striuggle - but after 2400 blocks, the difficulty will adjust down. That means it's easier to mine. (The difficulty is directly linked to the cost of mining as you need many more miners to win a block when the difficulty is high).
Basically you'll get iterations of this till the cost of mining falls below the bitcoin price. If the bitcoin price fell to $1 I expect you'll be able to mine them with your laptop as the professional mining farms will have long given up.
Good explanation bro.
Been wondering how this would work on Proof of Stake in terms of profitability. Proof of Works miners could easily sell off their mining equipments, use them for other coins or keep them until mining becomes profitable. But Proof of Stake people lose in several ways:
1. Their holdings devalue massively,
2. They will hardly mine enough coin commensurate with their stakes.
3. And worst of all, their coin is locked.
Seems the creators didn't anticipate this things
Well I wish this whole thing deters people from acquiring large mining equipments so that mining can be decentralized.