Just posting this here for those that don't look at the News pages much.
https://news.blizzard.com/en-gb/world-of-warcraft/21669947/battle-for-azeroth-collector-s-edition
Contains information on the collectors edition and a change in policy regarding upgrading from Standard pre-purchase to Collectors later. Previously a standard key would be given to you in return which you could use on another account or gift, this time they will credit your battle.net balance the cost of the standard copy. Full information in the blog linked above.
https://news.blizzard.com/en-gb/world-of-warcraft/21669947/battle-for-azeroth-collector-s-edition
Contains information on the collectors edition and a change in policy regarding upgrading from Standard pre-purchase to Collectors later. Previously a standard key would be given to you in return which you could use on another account or gift, this time they will credit your battle.net balance the cost of the standard copy. Full information in the blog linked above.