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