For years, HTTPS was regarded as only necessary for sites handling critical information, like bank portals. The movement for all sites to use HTTPS has gained traction over the past few years, partially thanks to the availability of free SSL/TLS certificates from Let's Encrypt, and partially thanks to browsers encouraging sites to switch. Starting with version 68, Chrome will start marking all HTTP sites as 'Not Secure.'
This shouldn't come as a surprise to anyone, especially since Chrome already marks HTTP pages with text fields as insecure when you enter any information. Google says that over 68% of Chrome traffic on both Android and Windows, as well as 78% of traffic on Chrome OS and Mac, is over a secure connection. Not only is HTTPS far more safe than HTTP, since all traffic is encrypted, but many new browser APIs only work on secure pages.
Mozilla is currently testing a similar mechanism in Firefox, where non-HTTPS pages will have a strike through the lock symbol, but there is no firm date for its rollout. Chrome 68 is expected to be released in July 2018.