Would say BTC is dead closer to $3000. At the least it would kill a huge amount of miners, close to 70% - reducing hash rate heavily. Not a security concern on BCH as no SegWit blocks.
Very low hashrate on SegWit blocks is dangerous - SegWit has achieved nothing by removing witness scripts outside of Tx headers!. Bitcoin (before SegWit) was designed min of 4 miners.
