Electric cars have fundamentally the same problem and Tesla decided to attack it by hiding some of the battery's capacity when the car is new. While the car might report to the user it is 100% full, it might only be actually 90% full. The battery can therefore lose a decent percent of its capacity before the user will ever notice the difference. This decision was made because cars obviously have a longer ownership cycle than phones and a drastic drop in range as a car ages is a huge flaw. But I do wonder if any phone companies might start to rethink this decision now that we are seeing some people use the same smartphone for 3-5 years.