When is SharePoint Online Classic Apps EOL?

I keep hearing that SharePoint Online Classic Apps are going away, but I can not find the official EOL anywhere. If it is true that the demise of classic apps is immanent, what is the timeline to bring the same functionalities from classic apps to the "modern" apps? Modern Calendar, forms, lists, etc., all work differently for communication sites and Team sites and vary on where you can find them. So, if SharePoint Admins around the internet are going to be turning on the panic alarms about the inevitable death of the apps we use, what is the official response? What is the EOL?