The max-level campaign being closed until launch makes sense. I assume that’s why it is currently “Wait for word from Alleria Windrunner.” However, if it’s going to be a week-by-week campaign it would kinda suck that we’ve been hyped on Earthen for weeks and Blizz made no indication it would be a timegated launch only for them to timegate the main expansion race. If it’s the case it’d be nice if they’d let us know for sure. Every response has been “just complete the level up campaign.”
Even this article about Early Access: https://news.blizzard.com/en-us/world-of-warcraft/24116738/world-of-warcraft-the-war-within-early-access-now-live#Earthen
Makes no indication that you cannot actually unlock Earthen in Early Access. Implying that you just need to complete the level up campaign and some side quests.