The pyramid of ages in Europe already started to inverse itself when I was a kid, we learned and studied that at school. The retirement scheme for public workers is not enough to assure the currently working population an income when they'll hit retirement age. By then, what those people paid all their life through taxes and contribution will barely be enough to cover their basic expenses, as some pensioners in Spain can confirm today. The whole current system should be scrapped, governments should encourage people to invest into private retirement schemes, but that would deprive these governments of a very big slice of cake. Keeping people in their job as long as possible has a double advantage. First, elderly active people contribute actively to the running of society and government expenses, and second, work keeps them away from hospitals and nursing homes. In the US, lots of people keep working beyond retirement in order to benefit from employer-financed healthcare cover. I think it would be a good option for Europe to implement that kind of healthcare cover, as universal healthcare is a major issue across the EU.
The bottom of the problem is to find a balance that would allow willing people to retire at their own chosen age without penalising the working population or keeping the youngsters away from much needed jobs... I am also in favour of a two to five years extra contribution to the workforce, to align the retirement age to the ever-expending life expectancy. Sadly, it means I will have to work until 70 to 72 years myself...