But those players have to understand that Lordaeron is contaminated, and even if it was retaken, it would not be suitable for living beings to live there.
So my solution for Lordaeron is as follows: detonate one of those arcane bombs that was used in Theramore in the sewers beneath Lordaeron (The Undercity). The explosion would cause the keep above the undercity to cave in and bury the Undercity.
Next, would be the cleansing of the remaining forsaken. Paladins like myself would offer those Forsaken who survived the explosion a choice:
Willingly come forward so we can end their curse of undeath and finally let them rest in peace
Leave Azeroth forever, never to return.
The land where Lordaeron once was would require many decades of healing and cleansing by druids.
Also a memorial dedicated to those who lost their lives to the plague in the third war should be constructed at the site.