As the AppointmentDialogViewModel is strictly bound to the ScheduleView, and only it can create it properly. So we strongly recommend that the AppointmentDialogViewModel is not used and that is why it is marked as obsolete.
So you should not worry it would not be deleted and you will be still able to use it if you asses that you need it.
Also if you have any other questions, please don't hesitate to write us.
the Telerik team