@pintadrew  WHEN Quickbooks completely removes Classic View, it should not be a surprise to you because THEY ARE ALREADY TELLING YOU THAT IS EXACTLY WHAT THEY ARE ABOUT TO DO.

Quickbooks is migrating all users to their "most up-to-date" version right now, but if you notice, they mention that they are allowing you to switch back to classic "FOR NOW." So Quickbooks are indeed warning you that you need to be working on migrating your accounting platform NOW. 

As inconvenient as you think it would be right now, just contemplate how much more difficult or IMPOSSIBLE it will be when much of your records are inaccessible once Modern View is your only option.