WOW will allow you to create inter-factional groups

Blizzard is working to create an Alliance and Horde player group for dungeons, raids, and rating battles in World of Warcraft. 

How inter-factional groups will work:

• The group will allow you to invite a player from another faction, if he is on the list of friends on BattleTag or the name of Battle.net, as well as if both gamers are part of the same factional community in WoW.
• Pre-assembled groups in the lists of the group search system for epoch-making dungeons, raids or rating arenas and battlefields will be open to players of both factions. However, the leader of the group will be able to make it available only to users of one faction.
• Guilds will remain assigned to members of one faction. The same is true for random groups - for example, for heroic dungeons, skirmishes or random battlefields.
• Peers from different factions will be hostile to each other in the open world, but will be able to communicate in group chat. At the same time, in dungeons, raids and ranking PvP matches, players become allies who can help in battles, exchange booty and gain joint achievements.

Fractional groups will appear in update 9.2.5, which will be released on the test server after the release of the content update "The end of eternity". By the way, the release date is near "The End of Eternity" not yet - only indefinite "very soon", said in November 2021.