Blizzard Entertainment has announced that World of Warcraft's next upcoming update, Patch 7.3.5, will be launching on January 16, 2018. This patch is intended as a bridge between the Legion expansion storyline and the next expansion, Battle for Azeroth.
The biggest addition in this patch is the new level scaling system. Like all the Legion expansion content, old WoW regions will can scale to players within certain level ranges. This gives players more options in where they want to quest and level up.
Unfortunately, while Blizzard was testing Allied Races on the Public Test Realms, they won't be a part of this patch. Allied Races are brand-new subraces for existing race options in the game, which need to be unlocked through questing and reputation gains. The Allied Races include the Highmountain Tauren, Nightborne Elves, Void Elves, and Lightforged Draenai. Players have been grinding out reputation with the expectation of playing the Allied Races in 7.3.5, but that's not the case.
The patch does have the new Ulduar Timewalking, allowing you to jump back to the classic Wrath of the Lich King raid. Players who have defeated the current raid content, Antorus, The Burning Throne, will be offered a new quest showing the impact of Legion's endgame events on the world. Other additions include the new Battleground map, Seething Shore, and an alternate method of obtain Legendary items in the game. Mythic Keystone Dungeons also have combat resurrection mechanics that match raids.
Players who are interested in the nitty gritty can check the patch notes.