I'm going to go against the grain here.
Gabby is almost 2 and still loves her dummy. She only has it for her naps and night-time sleeps. She's always been a brilliant sleeper but, yes, there are nights when she loses the dummy and I have to go in to give it back to her. It was worse when she was little and couldn't find the dummy herself and put it in her mouth. However, once she had the dummy she would go back to sleep without a fuss.
The dummy is a comfort for her. It's portable and handy.
I have no intention in taking it away from her any time soon. I've yet to see a child at school with a dummy so they do eventually get rid of it. I just don't see the point in taking away her comfort item when, quite frankly, it helps her to sleep and helps us to settle her when she needs settling.
I believe that she needs the language and understanding before we can negotiate with her to take it away. Perhaps give it to Santa one Christmas? That worked for my friend's 4yo.