I suspect the vast majority of people who drive cars until they fall apart are not buying the car when new, so aside from propping up resale, those users are not terribly relevant to manufacturers.
That "aside from" bit is extremely important. If car resale values drop, new car buyers will on average buy less frequently, and be willing to pay less when they do buy.
For what it's worth, my dad's diesel Nissan Patrol is about 20 years old now and still running fine. I mean, it's a bit clunky, but it does the job - and the 4wd has got me through some snowy roads, too. Good car. Beyond fuel economy, I don't see why that car needs to be decommissioned any time soon.
Any car will last for as long as you're willing to pour money into it. There becomes a breakeven point where maintenance costs increase such that it's cheaper to buy a new car than to keep the old one running. There's a good deal of variety in where that point occurs, due to different models having different reliability and different maintenance costs. Whether you're willing and able to do your own work on the car is also a big factor.
It may not have happened yet for that Patrol, but most cars are at that point by then, and it will probably happen soon on that one.
Lots of cars are kept beyond that breakeven point too, either for reasons of nostalgia, or because it's more palatable to spend your money in a continuous stream of small maintenance costs than to put down a big chunk up front.
Also though we have not had decent electric cars for long we've had electric golf carts for a while and googling the recommended life for accounting purposes it is 5 or 10 years. Just because a vehicle is electric doesn't mean it will last for ever.
the average car ownership time is somewhere around 6 years[1]. It feels like 3-year leases are becoming more and more common so I wouldn't be surprised to see this number drop significantly in the future.
