Miners make decisions based on the profitability of mining. BTC price is only 1 factor in profitability. Other factors are BTC transaction fees, increasing hash rates from next generation mining hardware and more miners entering the market. The beauty is that a market driven equilibrium will be reached driven by profitability. When mining profitability drops for whatever reason, some miners will exit the market and the remaining miners will see their profits increase. As long as people continue to transact in BTC, independent of price, some number of miners will exist.
RE: Bitcoin mining will exist only if the Bitcoin price goes up!