Google dictates the direction no matter if you look at blink or chromium. If Google wants to dictate a future where Brave cannot possibly do the work on chromium to implement their features because Google turned the code in a direction demanding too many development hours then they can easily do so. I completely agree with your last paragraph but using something Google in the end is controlling is closer to a honeypot than a solution. What we need is "a fast, capable, privacy-respecting, no BS, no ads or tracking browser with a sustainable business model, using whichever rendering engine (preferably one that is also well designed and fast)" on the market that isn't controlled by a big corporation like Google, Microsoft or Apple.

Sure it might be doable with blink but why on earth pick a fight where the opponent basically desides the rules? It's like pissing against the wind. I very much doubt it will succeed and if it does it will likely just swap Google out with another corporate entity (like Microsoft). We need a rendering engine made by someone like Mozilla (or better) to succeed if the open web is ever going to be a reality.