Full 1MB blocks with 7tps at $1 is $4200, at current prices it means that 2032 will be the time when fees (1$/1MB/7tps) will be 50% of the reward. But no on-chain growth potential.
Even with the current difficulty, $8400 is not much for the work you have to do to find a block. And difficulty surely will increase.. But I guess BTC price will increase a lot too.
If the price of Bitcoin dropped 90% it would just mean that only the 10% of miners that had the cheapest electricity would be able to mine profitably because the rest stopped mining.
Mining crypto will always be profitable for some, but not all, that try to mine it. Because the lower the price, the more people will stop mining decreasing relative difficulty.
