If segwit ends up having bugs, as some suspect it might, bitcoin cash is the logical replacement as every bitcoin older will own same number of coins. If that happened (segwit disaster) every bitcoin holder will support bitco7n cash, and with larger block size network scaling problem is taken care of.
Bitcoin cash is a segwit insurance policy.
Since a lot people sold their BCC, I don't think they will consider BCC as a backup of BTC even when segwit ends up having bugs.