Yeah, it may well end up being used for "maxipayments" too, as coupled with biometrics, perhaps.
But what will make it ubiquitous?
Also, there's something cumbersome and risky about using today's wallet apps. Imagine you're taking a train, about to buy a book on Amazon, and the guy next to you pulls out a knife and wants you to drain your wallet into his when he sees what you're doing. Or your computer is hacked somehow? Or you get a home invasion?
I think as money-printing keeps ramping up, people will just gravitate to crypto anyway.
But in the future, I expect AIs to become more common: at one point there was only Bitcoin and no long-tail of coins. And all these new AIs will need to be trained. Will x402 make that easy for them? How will the AIs access the new and original knowledge?
People will just expect AI as they expect sat-nav today in their cars, and eventually will expect self-driving cars. When was the last time you went into a library to access a physical encyclopedia? Banks may eventually fall away too as clusters of relationships form across the world to provides goods and services of value and seek refuge from tariffs but also access to resources.
Globalization is fine, but maybe the tech just wasn't/isn't ready yet? Cultural groups are also becoming increasingly intertwined too - but so are AI translation abilities.