I guess it would be a matter of the patience of the owners sinking money into them. As long as there is a supply of parts a car can run forever. The cars seem to have some serious mechanical defects that fail at low mileages. As long as you dont mind spending the money you could probably go on 2 or 3 transmissions and engines and keep on rolling forever until the Volvo dealer stopped selling the critical part you needed to keep your car useful :).

The only thing that will probably "getcha" is the interior and exterior of the car. Volvo is counting on these cars to be disposable (they have recycling symbols on all the interior plastic) so I doubt you will be able to buy a seat cover or seat frame assembly for a reasonable price when yours wears out. Other not critical to operation parts will probably become difficult to get in the future as these cars age. When the 2000's hit the 175k mark this will probably be when parts will become more scarce. Then again there will probably be a large number of non running 98's and other earlier models to scavenge from. So who knows really. Only time will tell :).

If you are proactive in your maint program you will probably be able to squeeze some extra life out of commonly failing components. When I had my S70 I found going with non Volvo parts decreased my failure ratio. When I switched to non Volvo brake pads my wheels stayed cleaner and my wheels stayed on the car longer without changing brakes every 30k miles. Perhaps someone out there will determine the failure issues with the Volvo A/C compressors and find a way around them.

Good luck

Robert.