My daughter was 5 and asked the same thing after our last trip. I asked the same thing you did. She said they were real, so I agreed. I will not lie to her about important things. I would never tell her that storks bring babies, etc. But, Disney, Santa, Easter Bunny, Tooth Fairy...I say believe as long as you can. I thought my time was limited. To hear some have made it until 9 gives me hope. I don't see any harm in believing. I think when the day comes, she won't be mad at me for the whole charade. I hope she appreciates all the "magic" I made happen. That won't happen until she is a mom trying to pull of some "magic" of her own.
I Believe!