Mining difficulty follows price, not the other way around.
If too many miners drop out, the difficulty automatically adjusts so that the block interval is still about the same.
It is elegant in that the more Bitcoin is worth, the more resources are put into protecting it.
you need a serious drop to instigate miners to drop out, also the diff retarget of bitcoin, is so slow is not even funny, by the time the miners leave the price will return at the first point, and miners will return as well