I will be quick because, in a way, I will be finishing up what my colleague Sarah has just mentioned.
Once again, it is a matter of the rhetoric we use. What does being overqualified mean? When we have a big labour shortage and when young people often come along loaded down with degrees but with very little practical field experience, you can easily turn the rhetoric of overqualification into the added value of being able to pass on knowledge. If an older worker is overqualified, so much the better. That means that he will be able to pass on his knowledge to younger workers.
That reminds me that I should mention that, to change stereotypical attitudes about older workers being underqualified or overqualified, younger workers absolutely have to be part of the equation. If young workers are not convinced that the older worker has something to offer them, the obstacles will always remain obstacles. So why not create teams with a wide age range? When there is a project to create a new piece of technological equipment, why put all the young workers together to work on it? Why should there not be a 60-year-old worker in the team too?
In fact, being in contact with different age groups and people of different ages is a really good way to break down stereotypes. That context is at micro level. But change can begin there, with initiatives where different generations exchange ideas and the overqualified complement the underqualified.