Assuming the vehicle had been maintained properly the lifespan would be around 20 years as said above. I've heard of some vehicles that work fine at 1,000,000 kms traveled.

After 20 years the car would still be fine, probably for the next 20, but then cars would have advanced enough to consider an upgrade.

Our older car is now 21 years old and works great. My tita has a Volkswagen Beetle that is also quite old but is good as new.