Google Calendar apparently will be getting a pretty hefty redesign in the fourth quarter of this year. That is according to a presentation being given in San Francisco (there was also an EMEA satellite event being held) at Cloud NEXT, where they were talking about the Product Roadmap for G Suite, 2017 and beyond. The video has since been pulled down, but there are still screenshots available showing the roadmap for Google Calendar and other G Suite products.
As you can see in the picture below, there are plans for a complete redesign of the web interface, as well as rich text in event nots on the web, side-by0-side calendar day view, see contact details within calendar view and discoverability of secondary calendars, all planned for the fourth quarter. Now there's not much else to see here in this roadmap, as there were no pictures shown about what the revamp or redesign may look like, but many users are thinking (and probably hoping) that it becomes a bit more material design-esque.
Google hasn't done a whole lot with Calendar in recent years. Google, and likely other companies, are thinking that users really don't use calendars all that much anymore. Of course, Google likely has plenty of data on that - how many users use the calendar, and how many just use it to see what day a specific date falls on. But it is nice to see that Google is working on a complete refresh of the web interface. It means that while Google Calendar hasn't gotten many updates recently, it hasn't been forgotten, and likely won't end up on their Spring Cleaning list, like many other products have in recent years.
The fourth quarter is still quite a ways away, so users of Google Calendar will need to wait quite a while before they can experience the new Google Calendar. It appears, looking at this roadmap, that there are some major changes coming to the entire interface of Calendar to make it better and easier to use. Now while this is in regards to G Suite, it doesn't mean that normal Gmail users won't get it. Actually Gmail users will likely see the refresh before G Suite users do.