My daughter just turned 3. She loves Dora, so we collected all the binkys for Dora so that she could give them to babies. Well, for about 3 days she would not take a nap, and I couldn't get her to go to bed like she used to. So, on her birthday, Dora came, and we gave her some binkys. We allowed my daughter to keep ONE in her bed. If she ever wanted it, she had to get in bed. So, she now puts herself to sleep for naps, and most of the time at night. I am very strict about it having to stay in her bed. She has a big girl bed by the way.
My daughter loves loves loves that thing. It was very sad for her to part with them. But, I am so glad we went with the one only option, because she is in control.
I know a lot of people are going to tell you she shouldn't even have it at all, way too old. But, I know what you mean, my daughter just loves that thing. Its one of her best friends. But, now its just less around. I know that she will get rid of it one day.
The big girl bed was a difficult transition though. Maybe keep it until that transition is over.
Hope it helps!