Tesla can either implement mobile device integration themselves or they can find a way to integrate 3rd party (CarPlay or AndroidAuto) products into the onboard software.
In the long run, it may be better for Tesla to focus on 3rd party software integration - which, in the long run, should require fewer Tesla software resources to support and evolve - than trying to stay competitive with their own mobile device integration.
Even before CarPlay and AndroidAuto are widely available, the Model S is already behind the integration offered in similarly and lower priced cars.
While the new calendar app is nice - higher priority should have been more safety-related features - such as hands free text messaging, something that's already available in other cars - even without CarPlay and AndroidAuto.
Hopefully V7 will show more integration - though if Tesla doesn't do something soon, they risk getting very far behind the other car manufacturers - and despite the large touchscreen display, the onboard software could be viewed as increasingly limited.