This reminds me. I have a new suggestion for my "Signature value" wishlist: ultra extended warranty. I'd be happy to pay for an additional 16 year extended warranty if the price isn't insane. Too bad WA sucks so I'll never be offered even 4 years.
Edit:
Perhaps a point of clarification is due...
While I have interest in upgrades/retrofits, enhancements (battery chemistry, supercharging rate), etc., my biggest concern by far is how much it's going to cost me to keep my car in working order for the first 20 years of its life. I haven't heard anything from Tesla recently that makes me less nervous about what happens after year 4 (or 50k miles). I'd like to trust them, but I'm really uncomfortable with the open-ended financial exposure.
Part of the issue is that I don't consider a trade-up "solution" as viable for a Signature combined with the absence of extended warranty for my location. Basically I have no outs other than to pay whatever Tesla decides to charge me for whatever goes wrong with the vehicle after the original warranty expires.
I'm fine buying laptops and replacing them every few years, but not a (Signature) Model S vehicle.
On the plus side, I have very high confidence Tesla will be around, as well as capable and willing to service the vehicle. It's purely a financial concern.