They can fully switch their power to this coin and who will then support BTC? Consensus must always be reached. The war is disadvantageous to anyone.
BCash has barely any liquidity to it, the majority of the miners mining BCash are keeping it without dumping just because of that.
Bitcoin's current network power is around 40,000PH while BCash hovers around 5500PH, it's impossible for anyone to profit from switching to BCash if its price doesn't rocket up at least x20.