You should have received an email regarding the 2.0 migration. If this is not the case I believe the Migrating Apps to Telerik Platform 2.0
article will answer most of your questions.
Additionally, I would like to note that if you are using the Visual Studio Extension and all your AppBuilder projects are available locally, you are not required to migrate them. However, if your apps are using one of the following services - Backend Services, Analytics or AppFeedback, you must migrate the respective service projects in Telerik Platform by following the instructions provided in the above link.
As for the AppBuilder project itself, its folder structure and files will not change. The migration concerns the Telerik Platform user experience mostly and doesn't affect the way you develop, build and debug your app.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items