There are no big differences between bitcoincash and bitcoin. so if bitcoin kills, higher quality projects such as ethereum rise to first place.
Yup, BCH is just another form of BTC with faster transfer speed and nothing more... If BTC dead, BCH will also dead..
There are a lot of other option other than BCH for faster transfer speed as there are a lot of ALTs out there. So yes I agree that ETH might be the option if somehow BTC failed us..
Even I think BTC won't be at that situation as BTC is the very 1st crypto that has a very great impact on other crypto coins ~