Tesla has promised the ability to swap out battery packs in the future. So, after 8 years the Model S should hold very good resale value because at that time you could probably swap in a 120+kwh battery (that goes 400+ miles). 30k residual value after 8 years on a well-options S 85kwh sounds about right IMO.
10 year old Tesla will be considered an ancient, inefficient design nobody will want to buy. Cool factor will be long gone. There will be much better cars and prices will be significantly lower than Tesla's today.
