Witch's Chin from Chin Implant?

CHCRAWFORD,
Witch's chin deformity may occur with any form of dental or plastic surgery around the chin. The mentalis muscle becomes loose from surgery or implants, resulting in a pointier or bulbous chin. The skin and soft tissue of the chin sags or droops.
Witch's deformity may occur spontaneously. More often it's due to dental surgery. Incisions that are intraoral (inside the mouth) or external (under the chin) may cause the deformity. Chin implants and augmentation, or replacing implants are also a risk.
Although relatively uncommon, having a plastic surgeon recognize the risk helps to manage and prevent the chin deformity from occurring, or treating the deformity.
If you feel your chin implant is too big or masculinizes your face, then it should be removed or exchanged. As with any procedure, you must weigh the risks, advantages, and disadvantages.
Speak with a plastic surgeon about chin deformities with chin implants and augmentation.

The risk of developing a "Witch's chin" after chin implant removal is minor. Such risk is higher if the implant is not replaced. If the problem is noted during surgery, re-suspension of the the muscle can be attempted. The fact that your plastic surgeon recognized and informed you of the risk speaks to his/her thoroughness.
Ultimately you will have to weigh the benefits vs. the risk of surgery. It may be helpful to obtain a second opinion. During the clinical examination the surgeon can gain a appreciation of the likelihood of complications associated with implant replacement.