User blog comment:Brandon Rhea/How we're testing the fandom.com domain migration/@comment-27467946-20181009104354/@comment-26437440-20181009125317

Yeah, no clue why they're being so hush-hush about exactly what communities. 3200 is a lot, but I'd settle just for seeing like 10 communities.

I've seen "We will be migrating several communities to fandom.com, including yours" on some wikis, so I guess those are getting moved first.