How I'd set up factions in a hypothetical WoW 2 set in the far future.

Lore background:
>There is an event in the future that changes the course of destiny for the Night Elves forever. Feeling betrayed by both the Alliance and Horde for the last time, with the death of Malfurion, Tyrande and her race are irrevocably changed. The Night Warrior envelops the whole of the race and vengeance and conquest begin to fuel their hearts. They break off from the Alliance and resolve to revive the Kaldorei Empire once more.
>The Draenei were also caught in the crossfire due to their close physical proximity to the Night Elves, and their own race has undertaken a similar epiphany. Unshackling themselves from the moniker of the Draenei, they are once more known only as Eredar, a race destined to conquer the stars. Perhaps Arz'al'kal intended for this from the beginning...
>The Forsaken, seeing little in common with the Horde & Alliance, having known that relations with tenuous at best with both, see an opportunity opening and join the other two in declaring war against both the Alliance & Horde. The Kaldorei decreeing that the use of Necromancy would be allowed within the Forsaken's ranks and no limits were to be imposed on them.
>With the death of Genn Greymane, the once close ties the two human kingdoms enjoyed is no more, and their curse evermore gnawing at the corners of their minds, they boldly strike out in fellowship with the Night Elves, no longer searching for a cure to their malady, but a path to acceptance of their bestial forms. They would then be known infamously as The Conclave, a world power that sought freedom through domination and power.

Horde & Alliance retreat back into their roots.