http://www.pcgamer.com/world-of-warcraft-will-soon-have-level-scaling-for-all-of-azeroth/

If you've tried leveling through World of Warcraft recently, you know how imperfect it is. You'll quickly outscale zones, and others you'll leave untouched entirely thanks to more rapid experience point gains. But in the upcoming 7.3.5 patch, Blizzard will be taking a version of Legion's level scaling and applying it to all of Azeroth and Warcraft's previous expansions.

During the World of Warcraft panel at Blizzcon 2017, game director Ion Hazzikostas took the stage to lay out plans for the next expansion, Battle for Azeroth. But these world-wide level scaling will be coming to the Public Test Realm servers in just a few weeks and then officially launch shortly after that.