After the events of Dragonflight you learn of something that can help you heal azeroth and fight the coming threat thousands of years into the past. Before the Titans ever arrived and when N’zoth and the old gods existed in their prime you travel backwards. Unlock the history of the past hidden to you by the titans, forge new alliances, and hide in secret to stand a chance to fight back via portals, underground tunnels, and a massive underground sanctuary in a crystal cave.
New racial skins
New specializations
Changes to the talent trees from lessons learned
New systems
New secondary stats
Mastery revisited
New M+ mode - No Timer
New Raids
10 more levels
Ultimate Raids
More story content than ever before
Normal is so redundant (easily out geared by overworld, of all things) it’s only run for mog and the glory achievements that don’t require heroic. Give it a bit more unf as far as rewards and mechanical demands (over LFR. They’ve been very comparable in the past two expansions), increase heroic to compensate.
There seems to be a huge gap from heroic to mythic that could be smoothed before we consider adding a whole new tier.