Most machines can last indefinitely with maintenance. The other day I used a printing press that was two hundred years old, was in basically continuous operation for much of that time, and is still used daily, today.
Cars have two obvious problems from a long-term maintenance standpoint: the steel chasis, which is protected from rust by paint. That will absolutely and inevitably rust. The second is that people don't understand maintenance. They'll happilly sit next to a machine that's screaming audibly for lack of oil, and think nothing of it. That's not something that will get better in the future.
Machines with controlled explosions inside them do not last indefinitely. A printing press and an internal combustion engine are not remotely the same from a maintenance standpoint.
Your point seems reasonable, but what's the part that actually breaks? There are lots of examples of ICEs that are over a hundred years old and still in use.
Presumably the engine block would work-harden over time, but it's already very hard and brittle, so I don't see what the problem would be there.
Rust is a major problem for northern countries, cars that would otherwise work ok for long just.. rust through if the body was not properly manufactured
Cars have two obvious problems from a long-term maintenance standpoint: the steel chasis, which is protected from rust by paint. That will absolutely and inevitably rust. The second is that people don't understand maintenance. They'll happilly sit next to a machine that's screaming audibly for lack of oil, and think nothing of it. That's not something that will get better in the future.