the UK will be caught in the middle and lose out.

Not part of US not part of EU either.

what a losing proposition.

if it can be a card network with fraud protections that visa offer -- this will easily overtake Visa, Mastercard

Brazil with Pix have already proved this.

> the UK will be caught in the middle and lose out.

Not necessarily

If we can have visa and MasterCard while not being part of the US, we can potentially take part in whatever the EU creates