The Inbox bundles seem to be slightly renamed categories that Gmail has, but with the ability that they're always on the main page and being able to create your own. Why couldn't this be easily ported back over to Gmail and tweaked with user config?
In Inbox I had a "Mailing List" bundle that had all my techy subscriptions and when I had free time I could see them. I could easily mark the entire bundle as read.
I'm tempted to start using one of my domains as my email address and point it at a different provider, but I'll see how Gmail fares over the next few months.