I see in these comments a lot of bitterness, where I think there should be opportunity: if you think Google made a mistake in killing Inbox and it was a feature beloved by many users.. why don't you spin up your version of it? They have already done the hard part for you: the idea.
When google killed greader, Feedly, The old Reader and other products rose up to the challenge. They felt there was market, and they launched (or just changed and marketed better) their product.
I believe that the hacker news general attitude is correct that the idea is not the hard part. The hard part is execution and getting adoption. Inbox works and is use by many. Hundreds of functional imitations can/will die, even when readily available on github.
When google killed greader, Feedly, The old Reader and other products rose up to the challenge. They felt there was market, and they launched (or just changed and marketed better) their product.
What is stopping you from doing the same now?