Why would US, or any region give all this trust and power to some 3rd party private company? They would basically give keys to break the financial system, or keep US as a hostage and making them vulnerable in time of crisis.
It is never going to happen. There are two types of concerns that people generally have, and one is a group that contains things like this. It sounds like a valid concern, but it is not. Nobody is going to allow any corporation to become that strong.
And banks partnering with Ripple doesn't mean anything. What are those partnerships exactly? Pilot programs? Institutions are constantly making all sorts of partnerships that are testing different systems. That doesn't mean they would lead to anything meaningful.
Firstly, it is just private companies partnering with other private companies. It does not mean that much. Second, I agree with you that most of these partnerships are empty marketing ideas that eventually lead to nowhere.
You are talking about blockchain proving to be superior, and SWIFT being obsolete, when it's clearly working 24/7, and you don't back up your claims with anything other then blockchain tech might be hard to scale (which is opposite of better). Blockchain is just a distributed ledger, and tech used to do it can vary a lot and it doesn't really make sense to call any of them superior, because they are not even comparable to existing tech. I can't see any way how that any of them are somehow "better" to adopt.
SWIFT is terrible and slow, but the reason that they keep it how it is is because they have complete control over it.