Can my baby wean himself naturally?

No. Not necessarily. While your milk will naturally decrease, and your baby will find nutrition in other places, he/she may continue to suckle because of the comfort and closeness to you during the nursing process. By offering an alternative to your baby, and minimizing access to your breast will help the weaning process more so.
Yes. If baby has begun to walk and seems more interested in exploring & less in feeding, he/she is weaning naturally. He/she may cut feeds short/ squirm to get off etc. & readily grab a sippy cup for later use...All signs of a natural wean. If baby clings to feeds & extends past 20m/side.Baby may be nurture hungry & require a longer process..With substitute nurture periods that are separate from feeds.