You are never too old for a baby blanket or a teddy bear.
On the other hand, the feeling of going from "I can't" to "I did" is empowering. If you can give up your baby blanket, its a step towards taking control of your own life. If you can break a decades-old habit, what else can you do? Get a better job? Finish a degree? Ask somebody on a date? Remember to take out the trash on your way out the door in the morning?
I'm not saying you should give up your baby blanket. I just think you should give it a couple of tries and see how it works out. If it doesn't, don't feel self-conscious; most people cuddle something or someone at night -- a teddy bear, a blanket, a romantic partner. If it does, it's one less thing to think about and one more thing you've accomplished.