We don't know exactly how this will look like but it is big change for them that will require a lot of work and adding support for selected coins as they clearly state they will not support all cryptocurrencies.
What we know from Mastercard requirements is that there will be strict compliance protocols and KYC with protection from money laundering and only regulated coins will be supported.
Positive thing: Many merchants and businesses will be able to use and accept Bitcoin payments very easy resulting in mass global adoption and billions of potential users.
Negative thing: They will surely use some centralized system with possible ban for any suspicious transactions, and they will probably hold private keys for any coins on their network.
In the end I am proposing a new logo for Mastercard
This move is probably gained from Visa but nevertheless it is still a great move which really promotes the use of Cryptocurrencies. The con's of this move is really scary because their network can be a target for getting the private keys and this has never happened in the Crypto Industry and might be the first if it even happen. Recognizing Bitcoin is a great thing but the security of this adoption might not be that great if they are gonna use a centralize system for it.