Well, at least you got a response from pg regarding Arc. Now, about that outdated Arc home and install page ... :)
EDIT
More seriously:
pg "In retrospect YC would have taken over my life no matter what. It has pushed out essays too, mostly.
I don't consider Arc to have died, incidentally. You used it to say that, and I'm using it to reply. If I ever retired from YC I'd probably start working on it more actively again." [1]
The thread was quite revealing. Or perhaps it just said what we all probably already knew.