That doesn't seem like as big a deal. Ad blocker users are not uncommon, but not the majority either. "Google users" is quite possibly the broadest demographic you could possibly lose.
I wouldn't be so sure. They probably rely significantly on enterprise/university/library subscribers. Journals haven't gone anywhere despite being paid forever. This will also switch to the journal bait and switch model. Show the abstract in google results, but require money to read the full article.
