They will continue to "work". Both v2 and v3 allows extensions to block elements from the DOM. However, only in v2 can they modify actual network calls. With v3, those network calls will still be made. Which means you are no longer protected from tracking and your web browsing experience is once again being slowed down by the loading of ads even if you don't see those ads
As I replied to your other comments, this is false. v3 block the network calls. They are not made. You are protected from tracking and nothing is slowed.
