> Hell, I bet there are insiders who were surprised about the decision to close up shop on Google Inbox.

Not an insider, but TBH, I was always pretty much sure that one of Gmail or Inbox will go away soon. With Gmail having more user base, it was natural for Inbox to be subsumed by gmail.

Inbox was not really fundamentally different from Gmail. It offered some new features, but I can't imagine that it would be too hard to implement them in Gmail too (e.g., snooze feature).