Just a little silly theory. Spitballing, basically.
Azeroth - Phase 0 - Elemental World
Just elementals everywhere. They ruled the planet, and there was no life. There's peace and harmony, with all the elements co-existing. But it doesn't last long.
Azeroth - Phase 1 - Disorder World
Still elementals everywhere. But Azeroth's world-soul is slurping Spirit energy so the elementals are a bit chaotic. Spirit is what brings harmony. This is tumultous time, with Elemental Lords and their forces waging war on each other. As the world-soul grows, more Spirit is consumed.
Azeroth - Phase 2 - Void World
Old Gods slam into Azeroth, seeking to infest it and claim the soul, and they eventually form the Black Empire near the center of Azeroth's largest continent.
War breaks out as the Elemental Lords band together to fight the Black Empire. But they lose, and are enslaved as a result.
The Old Gods start fighting each other in an endless civil war. "Only one would remain to consume the others."
Azeroth - Phase 3 - Order World
The Titans arrive and wage war on the Old Gods, through the titan-forged. First they beat the Elemental Lords and seal them in the Elemental Plane, and then Aman'Thul ripped Y'Shaarj out from the world, fearing he was too powerful for the titan-forged to beat. This caused the Well of Eternity.
The Titans then decided to imprison the remaining Old Gods, rather than take them out the same way. This ended the Black Empire.
The Ordering of Azeroth began, as the titan-forged shaped Kalimdor into a perfect continent.
Azeroth - Phase 4 - Living (and Dead) World
Life soon spread on Azeroth, both evolving naturally (seemingly enhanced by the Well of Eternity) and through the Curse of Flesh. The titan-forged took the backseat.
But life also brings death, and the great cycle was now the dominant force at play on Azeroth. Civilizations grew and faded away. Heroes were born, and they died. Bloodlines were started. Entire races of people came into being.
Azeroth - Phase 5 - Light World?
So what comes next? Well.
Tyr is associated with the Light. He's basically the father of all Paladins on Azeroth. His order is being reformed as we speak (the Tyr's Guard).
Odyn is associated with the Light. He used light-based abilities before he became a little bit infatuated with storms, he lives in a palace of light and has built an army of holy warriors (by the looks of it).
We've also got the Argent Crusade on the march, threatening to take Lordaeron, as well as a Paladin and Commander of the Army of Light serving as regent of Stormwind - the mightiest kingdom on Azeroth.
This has me thinking that, even if it doesn't happen right away, Light might be in the future for WoW. The question remains if it'll happen during 11.0, or if they'll perhaps save it for the distant future.
EDIT
Oh, and another thought. Why did the Well of Eternity cause life to blossom, unless there's more to it? For example, is Azeroth inherently life-affiliated, was Elune already a force on Azeroth before everybody else, influencing the Well of Eternity (essentially Azerite) to act as a life-booster specifically? Did she seed life on Azeroth in so doing? Or, was Elun'Ahir pivotal, having been the real reason why Aman'Thul accidentally created the Well of Eternity, and its roots then seeding life on Azeroth from within the primal realms of Life?