A new post about changes in launch skins appeared on the official website of the game.
Staring with Alexstrasza patch, Heroic Bundle will be deleted and they will be replaced by Skin Packs. They will be available for purchase for gems only. The skins can neither be found in Loot Chests not forged with shards.
Previously, launch skins could be either found in Loot Chests or bought from Collection, but now all colors for the skins will be available in Loot Chests or Skin Packs.