They could create self-contained Towers (or caverns, or something) (like Torghast) that would be perpetually placed in the game, in each races starting zone or something, to explain events, culture, etc. I posted my suggestion once before:
With how much the game has changed, the zones have changed, leveling, everything else? It would benefit them to create something in-game more permanent to provide new players with a place they could go to learn about each race and the battles / important moments in that race’s history.
Since it would be permanent, they could add ‘events’ and ‘stories’ within it as the expacs / game goes on.