I recall there being at least one content blocker that worked by heuristics instead of rulesets. Cannot remember the name, but it was clearly not as effective as conventional ones, because not all ads look the same and usually people want to block the invisible trackers as well.
Some Chromium browsers like Brave and Vivaldi already announced they’ll extend it for as long as they can, and when they no longer can’t, they’ll think of something else like improve their own blockers.