Although I love Inbox, it had no chance of being a $100 million dollar business. It would have been lucky to clear $10 million, even ignoring the fact that nearly all of its revenue would be cannibalized from gmail itself.
The odd part is that they developed a successful blueprint for how to beat their existing Gmail product and are apparently walking away from it. Anecdotal, but I don't know anyone who I introduced Inbox to that does not prefer it to standard Gmail. I wish they would focus their consolidation efforts on their awful messaging mess and leave Inbox alone.
Ah, but worry not, they've introduced many of the Inbox features back into Gmail! Except, you know, they didn't implement bundling, probably the single most useful feature of Inbox.
(If anyone can't tell, this is incredibly frustrating for me, since Inbox is going away soon.)
Ugh, the decision to kill of Inbox is what frustrates me the most. I don't think I can go back to regular mail after this. I'd love a self-hosted Gmail client that functions identically to Inbox, though (and perhaps is pluggable to other mail providers).
They should at least tell us what those projects are so someone can pick up the scraps.