Anything is possible if you're willing to pay. Tesla has a strong opportunity to help existing owners increase value and satisfaction by providing authorized retrofits. I know they're listening and I'm confident they'll do the right thing. In all my years of retrofitting stuff on cars the authorized kits have certainly been the easiest, but in some cars even the unauthorized aren't too difficult. I've seen everything from parking sensors to sound systems to transmissions and differentials, all depending on the manufacturer.
In terms of Model S, my list of things (ranked in order from easiest to hardest in my opinion) I'd like to see them consider. I only want a few of these, but I know others have expressed an interest.
1. Fog Lights
2. Parking sensors
3. Performance Plus Package
4. Rear Heated Seats/Subzero Package
5. Sound Studio
6. Rear-Facing Seats
7. Air Suspension
My only concern is pricing. I hope Tesla isn't as crazy as they have been in the past pricing certain accessories.
While my car is in service I initiated a conversation with my service advisor and concierge to see how difficult it would be to obtain part numbers and actual parts. I'm not sure if anybody has actually ordered parts for their car (or what type of pricing they're seeing) but I'm very much interested in the European tail lights (unless the new US ones blink amber) and some other stuff. Even if the retrofit isn't authorized for certain things, I'm happy to help anybody in any way I can to retrofit something to their car.