When Battle for Azeroth commences on the 14th of August for those who would normally get patches on a Tuesday and the 15th for those on a Wednesday. Blizzard had previously said that the game would be released on or about the 21st of September but they have brought the release date forwards.
Unlike in the previous expansions, there doesn't seem to be a lead antagonist, it has gone back to the roots of the original version. Queen Azshara, the once leader of the elves millenias ago will make an appearance in a raid in the future. It might well be that it is her who is stoking the rivalry between the two factions. What did start the renewed hatred of each other is the burning down of Teldrassil, the World Tree.
There's six new races, three aside which can be unlocked now through a series of scenarios, one player missions. The new races aren't as unique as previous races such as the Pandarens and Goblins, they are just varieties of old races such as Void Elves and Highmountain Taurens.
I know we not yet got into Battle for Azeroth but wonder where we go after, the planet of Azeroth is looking a bit cluttered now. Had originally thought that the Broken Isles would open a port to another world but that was not to be. Yes, Argus was opened up but they were just zones rather than a new planet.
There are six main zones, three that are Horde starting zones and three that are Alliance starting zone. Don't expect to see any of the other factions for the few hours until someone has reached the new maximum and then, they'll make their way over unless Blizz has something up their sleeves to keep everyone apart.