Is this part of the google monrepo? Not that it matters, but I wondered how far monrepo went, inside the tent.

I hate to be a pessimist, and I may be simply ignorant of some realities, but it FEELS like this is setting an impossibly high goal. I think there will turn out to be something significant in 9000 variances, which cannot simply be uplifted into mainstream, and which turn out to be hard to maintain as a continual rebase into the emerging mainstream.

I agree that 40 sounds low, but probably is a good indication it can work. 1% is within view, if they maintained pace so even on a 1% if the rebase cost can be handled, they can converge but that assumes there isn't a showbuster in the 9000.