will end all the horde hate when undeath gets a cure, but one that doesn't always work.
Think about it..all the alliance fan "horde favourtism" QQs may disappear altogether when humans also play a part in the horde by undeath being healable.. but not at 100% success rate, allowing you to still role an undead character or a horde human.
Would be a perfect intro with the new race models too. The story goes that some druid or Alextraszaa or a Naaru maybe even Elune implements a cure for undeath, but it restores some undead fully, partially works in others, and not at all in some. So you have the Forsaken group now made up restored humans/Elves and undead. To prevent human immortality, raising to undeath cannot be something that works all the time either, so it's success rate is going to have to change dramatically too.. burning to ashes or cutting someone to pieces should prevent them ever returning as undead too.
What do you think? it would give the horde a legitimacy for holding land in Azeroth the alliance fans can never complain about again, we could also finally give them their beloved High Elves, and i'd probably shift horde leadership to the Blood Elves again. Human forsaken will never forgive alliance humans for trying to exterminate them when they demonstrated they were free from the mindless scourge control and needed help rather than extermination. Maybe in light of that it's better if Blood elf priests find a cure.
Horde humans would have an additional character creation customisation - undeath scars or healing undeath which will allow you to have a fully normal human, or one wtih a few bits of rot that are "in the process of being healed" but not quite yet.