A couple things I noticed with the migration. I expected that it would not work when I did it because I had just purchased a movie earlier in the day before I read about this. Also, I did not disable family sharing because I figured my purchase would stop the migration. The migration was successful and everything transferred over. Family sharing is still working just fine and all my subscriptions carried over. When it completes, it says that you need to sign out of Media/Purchases with the old account on any other iOS devices/Macs/AppleTVs/HopePods and sign back in with your primary account. It also says the music library will take longer to carry over. I noticed that cloud library was now disabled on all my devices, however, I noticed my iPhone sync the library so when that happened I enabled cloud library on all my devices. Although they did sync, I noticed that I no longer see Recently played or recommendations in apple music (it looks like the home screen when you first sign up). Not sure if this was supposed to carry-over or if I turned on cloud library too quickly. All my playlists are synced and all my albums are there. As others mentioned, I had to unlink and re-link Movies Anywhere but luckily the 180-day wait period was not enforced. Up Next for the aTV app carried over my viewing history. Not sure why Apple Music did not.