Bitcoin and Bitcoin Cash can coexist peacfully, because it's different coins - Bitcoin is king of cryptos and Bitcoin Cash is just altcoin, which hardly can be used in our daily life.
I think that Bitcoin cap will grow much faster than Bitcoin Cash. I think that in future ratio will be 95:5 and this difference will continue to grow.
I think Bitcoin Cash is better than Bitcoin SegWit when it comes to transacting so I can say that it will not be hardly used in our daily life. Still, I am a user if bitcoin SegWit and not Bitcoin Cash.
For me, they can live with each other but with the user's not liking bitcoin cash, it will be 90:10 ratio.