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So in a few words only if miners can afford from their rewarded BTC, the mining cost. Only then bitcoin will survive. Due to halving, price will rise because if a miner finds pricy his equipment now, then he will retire 4 years later.
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There is no issue. There will always be miners. Don't forget that people were mining bitcoins when the block reward was worth less than $1.
The idea that
all miners will stop mining if the price is too low or the difficulty is too high is naive. No matter what the price is or what the difficulty is, some miners can make a profit and some can't.
When there will be less miners then those who are left will get benefited. What is amazing here is that this can be a microcosm of the bigger business environment where the law on supply and demand are carried out. In the next many decades, I am sure that mining Bitcoin can still be profitable but of course things can be more difficult so those who are creative enough are expected to survive and flourish while those who are not can be out of business.