I think some people overestimate how many will migrate to Firefox in the near future over this.
- High switching cost compared to finding another extension (e.g. uBO Lite), even if the resulting experience is worse.
- Just as many Firefox users like Firefox, lots of Chrome users enjoy what they have too. They don't want to lose that.
- The kind of tech-aware person who'd switch over this is much more likely to have seen the news months ago and taken action already.
As fun as it is to imagine an Adpocalypse shocking the masses and pushing them to try out alternatives to big tech, it's also way too optimistic, I feel.