I guess, but somewhere between 1/4 and 1/2 of people already use ad blockers. It’s not a small segment of the population. Even more people use some sort of plugin.
I think it is more likely that certain sites require secure mode; just like today. I guess I could be wrong, and most sites will end up doing it. I still suspect there will be a work around; even if it is as complicated as a secure browser being run in a virtual machine and then AI removing the ads to show you the ‘clean’ version.
I’ve worked on payment systems. It is very hard to federate unless something like Stripe is used for actual payment.
Credit card companies simply won’t interface with you unless you prove their data is safe. It isn’t a process that scales well.
Brick and mortar companies get around this by having payment terminals which are insanely locked down. (Which is also why those terminals mostly suck)