I've heard new 'content builder' will officially replace 'classic email' in SFMC - does anyone have the exact date of that happening?
With the January 2019 release, the ability to create new classic email content will be disabled. You'll still be able to edit and use existing content at that point. With the July 2019 release, the ability to edit existing content will go away. Existing content will still be available; you'll still be able to send existing emails and use existing content for an indefinite period of time. You'll also still be able to import classic content into Content Builder and create new emails in Content Builder based on classic emails.