Ok - but that won't happen (at least not yet, given the m3 api available, who knows what google will do long term).
The majority of users won't genuinely notice any difference between an adblocker running on m3 vs m2, and plenty of companies are going to make them.
My point is that despite the push back from the UBO dev (and I sort of agree - this does limit some capabilities, although not nearly as much as he claims) M3 is absolutely not going to kill the adblocker extensions available in chrome.
It just makes them... slightly minus. Which is why I think the name is a good call. I don't approve of the direction google is going, but this is not the deal breaker for any sort of public audience - it's just a talking point among the tech literate.