How are they going to be adding uBlock Origin to Chromium going forward if manifest v2 gets completely deprecated/removed entirely?
as of yet, there's no (publicly stated) contingency plan if the upstream mv2 code is excised, but I could be mistaken.
all of that being said, I was answering the question about mv2 broadly, not ad blocking.
I'm not sure what Opera/Vivaldi/et al. use for their native adblocking, but Brave's rust adblocker makes the most sense to me. Really it's uBlock's filtering lists that keep the whole thing working anyway.