I don't think there is hope if you look at actuarial tables and Knuth's age. It's not clear to me if he'll be able to finish volume 4. The outline he has seems to have enough material to fill volumes 4C-4G to my eyes, and he isn't exactly cranking out the volumes.

Admittedly, volumes 5-7 wouldn't be as massive as volume 4 (it sort of turns out that almost all interesting algorithms ends up being categorized as being in volume 4), so you probably wouldn't have a half-dozen subvolumes per topic but, it's still too many books down the line, especially if he plans to revise volumes 1-3 before working on anything else.

I hope that God is indeed willing, but the man is 88 years old and he’s not done with the third tome of volume four. It would require a minor miracle for him to finish volume 7 within this lifetime.

I really hope he ends up completing the whole series. I started volume one recently and it is excellent