There are people asking questions about encrypted access token and OAuth 2.0.
FYI, the encrypted access token migration option in your Facebook App setting is just to control whether your app will be receiving an encrypted access token or not. If your app does not try to parse the access token (some people are trying to get the user ID from the token), then your apps should not be affected with this change.
This should not affect migrating your app to use OAuth 2.0 for authentication (though it is part of the OAuth2 spec). OAuth 2.0 is available on the FB Platform for a long time already and once you migrated your code to use OAuth2.0, you can start testing it.
Hope this clarifies.