I've seen some new research from Talent Q showing that older workers can often be the most flexible.  They conducted "in-depth analysis" of over 5,700 workers reveals and found that as people get older they become increasingly willing to take on new tasks and more varied roles....

The research challenges the common preconception that older workers are unwilling to accommodate change and that they may be unresponsive to new challenges presented in the workplace. 

The study had numerous positive findings, with older workers being happy to work on their own and take a leading role without the need for much guidance.  They also demonstrate a high level of ability in building successful working relationships with colleagues, clients and suppliers.  Intelligence testing revealed that older workers’ verbal reasoning was as good as that of their younger colleagues and while they may take longer to calculate answers to numerical problems, they are equally able to answer correctly.

While it was shown that workers in their fifties and sixties are much less ambitious than their younger colleagues, this is probably just an indication that they have already achieved their goals or have decided that they are happy with their lot in life.