- Build a full ad blocker into Firefox natively
- Put out a huge ad campaign that just says "This could be the last ad you ever see—try Firefox, now with built-in ad blocking
This would've worked way better prior to Brave, though.

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This would've worked way better prior to Brave, though.
you could even skip (1) if you just included ublock origin in the applicayion bundle and slapped a Firefox Privacy Edition logo on lol
Obviously they would lose their Google funding real fast if they did that
Maybe. The money Moz gets from the search deal has not dropped as it's user share has, so the money is not entirely based on pure royalties, and I'm not convinced Google would cancel the deal based only on that, given how it plays a part in their defense against monopoly lawsuits. If it defaults to being off perhaps the users who don't bother turning it on would be enough.
Had we done it when we had like 30% market share and we're still working with advertisers on things like Do Not Track, it would've had a much better chance at forcing development of funding models based on things besides advertising, too. That would've been the best time to try, but alas. We did not.