It is now common knowledge that the population of Burning Crusade Classic is down significantly since the initial boom. This was acknowledged by Blizzard in a post.
According to the studio, due to low population, 21 realms will be taken down on August 10th. However, players will still be able to transfer to other servers for free.
Blizzard will also remove a gatekeeping mechanism for transfers: "In coming weeks, we plan on removing the restriction on transfers between normal and PvP realms of Burning Crusade Classic. We will then allow character transfers from underpopulated normal realms to be free. Additionally, we will eliminate the PvP realms rule that prevents players having characters in both factions of the same PvP realm in Burning Crusade Classic.
In other Blizzard news, the Diablo II: Resurrected team announced that they are working on a "significant upgrade" to the lobby system over the next few weeks.