Grid Layout is also shipping in Safari soon - it is in the current beta. The work on implementing Grid Layout in WebKit was performed by the same team at Igalia who did the work for Blink, the engine behind Chrome. Manuel Rego, one of those implementors gives an overview of grid in this post for the WebKit blog.
"There is also vmin, which is the lesser of vw and vh, and vmax, which is the greater. "
It has to be said, I've often drawn a blank when thinking of a good use case when teaching vmin and vmax, here is one such use case explained.
Not layout directly, but very important as we get excited about new possibilities. Bruce writes about the World Wide Web and the fact that outside of the West people rely on Smartphones and expensive data to use the web. Bruce has also followed up with a part two of this article.
These are long pieces but well worth your time, and include practical information in addition to eye-opening statistics.
A nice article on designing better cards, something that seems very simple but hides a lot of detail. I like using "the simple card" as an example in tutorials because there is always more than meets the eye. This is a nice take from a design point of view.
After grid, the topic that I hear most about from experienced front-end developers is Container Queries. Here is an excellent article from Ethan Marcotte, explaining what they are, and why we need them.