Yes. Some elderly people have sex. They might have to change some habits and routines but they may remain (to some degree) sexually active. Humans are full of desire and just because someone is aging it doesn't mean that they lose this passion and sexual desire.

I think sometimes it is really hard to imagine when you are young that older people are also dealing with sexuality just as you and your friends are, but this is true.

I used to spend hours wondering whether or not my teachers were sexually active. It didn't even seem remotely possible. But whether or not they were sexually active is not really the point. The point is that they were sexual beings like myself. I believe that people's relationship to their bodies and to sex is always evolving and finding new outlets.