At some point an equivalent product could be offered as a replacement. Or parts could be replaced. The cost of this will be reflected in the price of the warranty which also serves as a down payment for a replacement product. But still, the producer will have an incentive to do an honest assessment of the longevity of the product via the cost of the warranty. Too low will cost the company and too high will shy away the consumer.

Buildings fail over time. Yet when you rent a flat you have a reasonable expectation that it won't collapse on you. Perhaps there is a good function between product age and monthly warranty cost that creates the right incentive.