I would mention of situations where Bitcoin is complementary as opposed to a replacement to Visa / Mastercard

Here are some examples: Can you use Visa / Mastercard to:
Give money to a busker?
Give money to a homeless person?
Pay the kid next door to do some work in the yard?
Give an allowance to you kids? Note: See pre paid fees below.
Pay your babysitter?
Reimburse an employee for expenses as a small business person?
Pay any consumer / private individual?
Buy products or services online if you have no credit or poor credit? Note: Paying 20 USD or more in fees for a pre paid debit card to purchase a 20 USD item is not the answer.
Purchase a product or service from a merchant that does not have a merchant account?
Send money to a relative that lives in a remote village in Kenya?
Pay for high value low margin items online such as gold bullion coins for example?  
...

All of these work with Bitcoin but not with Visa / Mastercard