If Brave can reach this point it would be great, but then they are still at the whim of Google, who has shown little to no interest with privacy in Chromium. To overcome this they would start needing a team as knowledable as Chromium's and Firefox's to maintain a codebase that has diverged so much from Chromium because of their desire to uphold privacy in the face of fundamental changes Google impose.
At this point I think they'll almost have come full circle with where Mozilla is at, where they are struggling to make enough money from it's users to stay afloat. I think this is why it's so important to support Firefox, in the same way for Linux desktop. There's no telling how long it will take for Brave to reach this point (if they ever do), whereas Firefox is already there now.