Pampered hardware will likely last 5 years. Hinges, back lit screens...they can be unpredictable. More likely is that rapid hardware advancement will make a newer version faster, cheaper and better. Absent a hardware failure, you're more likely to face a desire for a model that does more.
However, compared to what many experience with Windows PCs, I expect the productive life of Chromebooks to be longer because they free us of the headaches of registry, drive and malware deterioration.
However, compared to what many experience with Windows PCs, I expect the productive life of Chromebooks to be longer because they free us of the headaches of registry, drive and malware deterioration.