I don't believe aging is as relevant to F1 as it is in other sports, as long as the driver can retain a certain level of fitness. One of the key points in succeeding in F1 even at an older age is adaptability, fitness, a fast car (duh) and a great team around you.
If Federer can still compete at the highest level of Tennis at 38.5, then Hamilton can easily remain competitive at his age and more.
Not for nothing, Rosberg's Championship is the only thing that lends credibility to Hamilton's recent success. Otherwise, he'd just be the guy who's had the best car. — bhall II