They've done this many times before. The last time was in 2016 when they shut down https://en.wikipedia.org/wiki/Nostalrius https://en.wikipedia.org/wiki/Nostal

They've done this many times before. The last time was in 2016 when they shut down https://en.wikipedia.org/wiki/Nostalrius https://en.wikipedia.org/wiki/Nostalrius which is what lead directly to WoW Classic. Before that, they've done several bi-yearly waves of shutdowns. There's still hundreds of repositories on github that contain versions of this code used for various servers.