Fork or not, they obviously integrated almost everything from the upstream. Keeping a long-running fork that's increasingly diverging is not a simple task.

Does Brave have the man-power to sustain their fork if it diverges sufficiently that they can no longer integrate upstream changes?

EDIT: My broader point being, Brave's mission is less compatible with Google's and as such it's unfortunate they aren't basing Brave on Gecko.

I know the whole history with Brendan Eich and Mozilla, as well as the problems with extending and embedding Gecko. Still, seems like an unfortunate outcome