It's not a matter of "might not work in the future," it would be broken on arrival due to the limited abilities offered by the current extension APIs. As for F

It's not a matter of "might not work in the future," it would be broken on arrival due to the limited abilities offered by the current extension APIs. As for Firefox vs Brave, I would encourage you to check out the independent study by Leith, of Trinity College in Dublin. Leith found Brave to be in its own class as the "most private" browser tested (including Firefox): https://www.scss.tcd.ie/Doug.Leith/pubs/browser_privacy.pdf https://www.scss.tcd.ie/Doug.Leith/pubs/browser_privacy.pdf. You could perform a similar test yourself. Setup Fiddler on your machine (installing the root cert to inspect HTTPS traffic), set aside %localappdata%/Mozilla and %appdata%/Mozilla, then launch Firefox. The traffic (without any user interaction) is a surprise to many. Compare with Brave (be sure to set aside %localappdata%/BraveSoftware beforehand).