2shoes, I hate to say this, but are you deliberately missing lots of the points being made?
A dummy or bottle can be harmful to tooth development, breastfeeding cannot and is in fact, helpful to too development.
As has also been said, breastmilk continues to be beneficial both healthwise and nutritionally for as long as the child has it, it doesn't suddenly change to water or lose it's nutritional value at any point, in fact, it adapts to the changing needs of the child to suit those needs.
Children who breastfeed, at any age, are recieving nutrition as well as comfort. They may not 'need' breastmilk for nutrition, but it benefits them, so why not? They don't 'need' cows milk. Or carrots, or potatoes, but if they all make up a part of a balanced diet, why shouldn't human milk too?
From my own point of view, I intend to continue to BF until DD self weans. That may be when she's 2 or it may be when she's 7. I'll continue because it is beneficial for her and it's also a lot easier than going down the parent led weaning route. However, even now when she is still under a year old, there are times when I don't really like breastfeeding her (being pinched, poked, prodded and kicked in the face is not my idea of a laugh, oddly... ) so it's never going to be because it's what I want for myself or because I benefit from it in some way.