People will turn to Bitcoin Cash eventually.
Alternative to bitcoin (a decentralized currency with immutable blockchain) is not bitcoin cash (a centralized garbage with a mutable blockchain). Not to mention that it is the exact copy of bitcoin that suffers from the same scaling issues.
If people some day turn away from bitcoin they will seek an actual alternative that provides them with the same characteristics such as being decentralized, immutable and have a better scaling tactic.
Might as well use your Mastercard. It will save you money.
If you think the only concern when it comes to using bitcoin versus mastercard is the fees then discussing things further with you is pointless.