At one point IE was just as dominant as Chrome is today, and it got displaced. A lot of people seem unable to imagine how Chrome could be displaced today, but that can happen pretty rapidly. For example, Google restricting ad blockers on Chrome will almost certainly drive Firefox market share up. However, the only reason this is possible is because we have web standards that are independent of a single browser and ve…
Anyway the adblocking thing isn't really related. Extension APIs are not industry standards, Chrome already doesn't allow adblocking on mobile, and maybe at some point they'll just write off the users who care and focus on monetizing the users who will put up with ads.