They're not interested in making the vision of cryptocurrency a reality any more than it enhances their bottom line.

Mastercard is offering exchange services. They will collect exchange fees on transactions, just like PayPal and other providers.

They won't even bring blockchain into this any more than necessary. They'll handle it in databases like everyone else, only engaging with the blockchain as necessary for deposits and withdrawals.

In fact, for every transaction where a unit of cryptocurrency is bought, that same unit is also sold.

yeah sold for a candy bar and the merchant still has the cryptocurrency and pays their overhead costs in the same cryptocurrency who buy their own candy bars from a different merchant in cryotocurrency

Payment networks like mastercard integrating cryptocurrency make this more practical instead of handwaiving a gradual organic adoption idea