I agree with you say about BAT becoming more popular, but I can see the gaps.

Brave browser needs a bid based advertising platform like Adwords to push the ads into the browser.

I tried the VeraWallet and played with the rewards program. What I find is the overlay opens within the video itself, and if you're using Brave (track blockers) you're asked to verify via Google reCapture and it open somewhere random where you can't see it. That bug alone would see a lot of people drop off.