Some players had been toying with the idea of catching up with their Scarab Lord with the new realms that are releasing with the pre-patch for Wrath of the Lich King Classic. This led to a lot of speculation in the forums, although the announcement clearly states the following.
All of the WoW Classic and Burning Crusade dungeons and zones will be unlocked and available on these realms. On all realms, Northrend will be locked until Wrath’s official launch day.
Community Manager Kaivax
This text clearly states that all Classic and BC zones are unlocked. This also includes the AQ event.
In order to remove the last doubt, WoW developer Pazorax recently spoke out.
Thanks for asking!
WoW Developer Pazorax
I suppose we could have been more explicit in the original announcement post, but the relevant line is this one:
All of the WoW Classic and Burning Crusade dungeons and zones will be unlocked and available on these realms.
That includes the gates of Ahn’Qiraj; they’ll be open. The war effort will be marked completed. The gong will already be rung. The Anubisath warriors will already be beaten back. The fresh Wrath of the Lich King realms will not mint any new Scarab Lords.
If you want to be a Scarab Lord, consider organizing the effort on a low-population Season of Mastery realm. Last I checked there were a few with their resources completed but their gongs unrung…
Source: us.forums.blizzard.com