Brave isn't implementing v3 immediately, but Chromium is their upstream and I haven't seen them claim they will be able to resist indefinitely. They have their own non-extension adblocker for which v3/no-v3 is irrelevant.
Eich later in the thread you linked said this: https://twitter.com/BrendanEich/status/1534905779630661633
If your business depends on the idea that Big Tech can not track you, you need to do whatever it takes to keep it a reality. The cost of supporting a fork of Chromium might be too much when you are starting out, but when you are already a company of 100+ employees and 60M+ MAU, it becomes acceptable.
So, yes, if I had to guess with the information currently available, I'd say that Brave will keep away from v2 as long as it possible and as long ad the user base shows that this is what they want from their browser.
(Not sure where 'semantics' came from in the first place here.)