There is an interesting discussion on uBlock Origin/uBlock-issues about the upcoming Chromium extension manifest v3 that includes important changes to the webRequest API in favor of the declarativeNetRequest API. It seems that the latter will only support the AdBlock Plus filter syntax up to a maximum number of 30,000 rules. Some participants fear that the webRequest API will be phased out. @gorhill's reply: However, it seems that the webRequest will not be completely phased out but will be limited somehow: Note that this is still a proposal and it has to be seen what will finally come out of this. Depending on what they decide there is a risk that important functions in uBO will no longer be available and uMatrix won't probably work at all any longer. This would probably affect all Chromium-based browsers. One participant in that thread thinks that such a move would not really be surprising considering that Chrome recently added its own light-weight adblocker. In any case, Firefox would certainly benefit from such a move - unless they follow this strategy. I don't think they will as this would be incredibly stupid. Even right now Firefox offers webextension APIs not available in Chromium from which uBO benefits.