Agree with mcv1, DD1 loved her dummy but by the time she was about 2.5 yrs we were down to just 2 of the type she liked and they had stopped making them. So it was time for the dummy fairy. We had a little chat about it and asked her what she would like the dummy fairy to bring her. Gift bought and exchange made one night and she never asked for it again.
I think the trick is to wait until you know they are really ready, old enough to talk about it and understand the dummy is going and will not be back.
Do you find this a real problem? My children loved their dummies, after a certain age I restricted the dummy to bed time, and when that became an issue i.e when they were waking in the night because they had lost it then the dummy fairy came to take it away to give it to a baby who needed one and left them a small gift in return. Within 4 nights they were used to going to sleep without it with no problems, but I would advise once you decide to take it away, never give in and give it back as next time you try it will be really difficult x
Dd is 2, and still likes her dummy for sleepy times. But it's the association she knows now. So if I say are you feeling tired? " dummy please mummy", or get her out of the shower ready for bed " dummy mummy"
Sometimes in the car she'll fall asleep without one but she's always been a sucky baby (was breastfed to 13.5m) but just still likes the comfort of her dummy and blanket when tired