I can't drive so that isn't a major issue for me - although my husband does. Luckily, I live in London where public transport is very good.
Obviously, things like dementia and general ill health or incapacity are a worry as you get older. But I can also identify with Elena's response of fearing becoming a "bore". I think, mainly because elderly people are more likely to be less mobile and more isolated, they tend to become more focused on themselves - their health, their likes and dislikes, etc., etc., and less focused on other people and what's going on in the world.
Also, I do think there's a tendency for older people to be overlooked and undervalued in our society - and a view that they form some sort of amorphous lump of like-minded people which, as Gransnet demonstrates, couldn't be further from the truth. I've noticed that, for instance, holiday companies that have a particular appeal for older people - such as Warners - always seem to include such activities as bingo, bowls, ballroom dancing, etc., which, I think, reinforces a very stereotypical view of old age.