+ Many (or potentially all of the backers except Facebook) will withdraw from the alliance.
+ Facebook/Zuckerberg will defy the gov.s and launch Libra.
+ Libra might not dominate the world, but it'll be a success (at least a niche success) and it'll eat up some of the marketshare of these financial institutions.
I think Zuckerberg has come (or already know) to the realization that these institutions "added value" is navigating the regulations/laws of the different countries. They are a kind of monopoly. Sending money across "borders" is hard only because governments made it so. If Libra ignored these rules, they'll put these guys (or at least a part of their offerings) out of business. Why would anybody use Western Union if they can send money through their Facebook for less or no fees? It's easier and more convenient too.