How many yrs or km will you do before your next car ? I guess 5yrs or 50K should be minimum.
Some like to keep it for much longer. Those who upgrade quickly usually think they can get good value for selling a 5yrs old car and buy similar but modern car. Those who keep it for longer and get maximum out it probably go for big upgrade and not much for selling their 15yrs old car. Probably still keep if it runs without too much hassle. I have seen what looked like 90's model Mercedes. May be not the first owner but I think that car surely was 15+yrs old. Old model Toyota Corolla's and I still see lots of santro's too.
Just for curiosity wanted to know about others ?
PS: I choose the third option