> This would still rely on Visa/MasterCard allowing dual-branded credit cards for overseas transactions, which isn't a very common arrangement

We can and should make this practice illegal, along with several other anticompetitive policies in this space. Oh no they might hit us with tariffs in response?

You can do this in multiple steps. Start with a credit card usable only with Canadian merchants, which will cover a great majority of transactions of a great majority of Canadians. I'll have an MC for travel and the ordering from non-Canadian merchants, and this Canadian credit card for the other 95% of my expenses. If a significant percentage of Canadians have such a card, major non-Canadian services will add it as a payment option (e.g. ChatGPT or Claude). Then you branch out by either joining or co-branding with the EU credit card company if such a company succeeds.

A world with a patchwork of payments processing options will look different for travel and business, in some ways worse, but such is life in a "multipolar world" which the Americans elected their leadership to conjure up.