What age is too old for a pacifier?

we have a 20 month old daughter. she is very attached to her nuk. I'm allowing her to still have it because she has a new brother and is having trouble adjusting. My husband and i have different ideas on when to take away the nuk. I say 2 years old and he says 3 years old. I was just curious what other people's opinions on that are. no rude answers please