Mozilla/Firefox needs a niche? I'll give them one (free of charge) - right here, right now.
You want me to stop using Chrome? Actively block ads 100% of the time. All ads all the time. Blacklist sites that pump out ads. Block nasty javascript that tries to load ads. Just do it. As a consumer, when a website breaks because they don't want to agree to the 'new' Firefox, I'll take on that battle as long as Firefox gives me the protection I ask for.
Then, to get revenue, because now you'll have a very strong niche of advocates, set out 'advertising guidelines' so that all ads must be non-intrusive, can only fit on a select portion of the screen, must not have pop-ups or music or anything - effectively 'newspaper' ads (they can't do anything other than exist).
Also, make semi-incognito the default (actively block all cookies that are known to be tracking/advertising). Cross-site scripting should be very limited too (and I really don't want to see a ton of sneaky iframes to get around this).
If you do that - I'll use it regularly (currently I only use Firefox because there is a particular website I like that caters to it)
