They covered it pretty well and have a better handle on it than those of us on the outside looking in.
You may have noticed with the launch of Classic Hardcore that there weren’t a lot of realms. Was Hardcore’s launch a small experience? Heck no! Hardcore continues to be experienced by a huge number of players, and we have been thrilled to see so many players, new and old, join in to experience World of Warcraft Classic in a new, exciting way. At the outset of any launch, our goal has always been to create healthy, enduring realms, and behind the scenes, we deployed tech in patch 1.14.4 that allowed us to significantly increase the realm capacity of a single Classic Era realm. With this higher realm capacity and fewer realms, we avoided the need for disruptive character migration options as realm populations ebbed and flowed.
For Season of Discovery, we’re going to repeat this process. We will launch a handful of realms that can support a lot of players, so you can feel confident in your choice of realm. Please note: we will actively manage the realm sizes at launch, so you might see sporadic queues as the populations spread out and we ensure realm sizes remain roughly equal. If Season of Discovery proves hugely popular (as we think it might!), we will of course be ready with additional realms if needed.
They’ll launch the servers they feel are necessary and will add more if needed but they apparently want to avoid “disruptive character migration options”.