So, what exactly do we do when DJI moves on and stops support for the P3 series which requires phoning home for permission to fly whenever a change is made? We can't expect to never have a need to change firmware, computer, phone, app, etc, and each change requires a "check in" to confirm it's good to go. DJI isn't likely to keep this link alive forever.

Drones such as the P3 have only existed for about 16 months and the usual life of these products is 12-24 months (crashes or wanting to upgrade often means end of life).
I'm sure DJI will keep things alive for at least that long.

I'm still using my P1 from years ago - no problem.

Technology get's obsolete, it happens. Look at Macs for example priced high and the computer market moves so fast they even say old devices can't get new software and support stops. Same for Microsoft Windows. The ideal answer is simple - upgrade.

However the phantom is really software driven and by then end of it's life cycle I would assume that DJI has a solid working product that will live until the user crashes.