When it comes to the financial system, the thing that gets most companies is regulation. As much as these tech companies want to play bank, they just don't have the right skillset to navigate the complexity of regulations across multiple regions. Finance's problem isn't tech. People assume the issue with a banks payment system is the fact that it runs on some mainframe running Cobol. False. The main problem is that the payment and settlements network is established and works well enough that there's really little actual value in investing any further to upgrade it. Many banks did jump on the bandwagon of blockchain, hoping it might solve some of the challenges of inter-bank settlements, but it hasn't panned out the way they thought (basically think back-office employees who do much of the settlement verification being replaced or automated away). Facebook has less than a percentage point of a chance of upending current payment networks. Even starting from today it would take them at least 20 years to effectively build up the competence to navigate the politics and regulation of our current financial system. Do you remember the hype surrounding Zucks day infront of congress? Guess what...that happens almost annually for a bank and it never makes the news. Forget the well established lobby banks have that FB and other tech companies don't even come close to achieving.
Visa is doing the smart thing and investing in this as it will probably find some traction given FB's reach, but poses almost no real threat to Visa in anyway. Personal and Commercial banks' main business isn't really payments, but rather loans. They offer payments since they already have a well established settlements network and serve as gatekeepers to the financial system.
I'd love to see where this goes, but I have a really hard time believing that this will grow beyond anything but another FB digital currency. There's a fundamental aspect of currency where it's tied to a government as well as a country and it's world dominance. There's a reason the USD is the reserve currency of the world, and yet another reason the government is the owner of the USD. Bitcoin at least tried to challenge this dominance. FB isn't even thinking like that clearly. They have another play in mind, and frankly it's not entirely clear what it is.