With all the valkyrie gone and sylvanas staying in the shadowlands. We effectively have no leader, and now way to increase our numbers. Sylvanas made a good point in cataclysm. Without a way to replenish our numbers we will slowly die out. We may not die from age but there is always conflict in Azeroth. Even if we make peace with the alliance there will still be things that reduce our numbers over time. We are a race we don’t deserve to die out. But raising fully sentient undead is not easy task and we wouldn’t trust most necromancers because if they’re powerful enough to do that they’re also powerful enough to seize control of our minds and bodies like Arthas did. It’s a precarious situation.
If we CAN find a way to raise the dead the logical course of action to ethically reproduce in return to life various mortal races of azeroth who have died and give them a choice: A second chance at life as a forsaken, or back to the grave. That seems perfectly ethical. Everyone we encounter will be given a second chance and they are free to reject it if they so please.
But the core question remains. Bolvar could’ve potentially been an answer but he is no longer lich king either. And… I think some might not feel too happy about another lich king raising the dead even with different motives. In legion the knights of the ebon blade were able to resurrect folks as death knights which I believe takes a lot more oomph than being resurrected as a typical undead. Still the ebon blade are their own people doing their own thing. I doubt they’ll want to be roaming the land resurrecting the dead.
Perhaps we could turn to engineering. Create a device, a form of technology that can raise the dead with their minds intact without being able to enthrall them. But is that even possible and where would we start? I suppose we have the time. We aren’t going extinct any time soon but I believe our culture is worth preserving.