I'm still mad about Inbox. I moved over to it from Gmail because they said that it was going to be the future of Gmail when it launched. Instead, they abandoned it.
Many of Inbox's features were moved over, such as Snoozing emails, but far from all of the features. I doubt they will move over more — if they had wanted to they would have done it when they shut down Inbox.
The biggest feature I miss from Inbox is the integration of TODOs and emails: you could create editable TODOs in your inbox as easily as composing a new email, and when viewing am email thread, you could create a TODO attached to an email thread (e.g. “review the attached document and reply with my feedback”).