Do you think this would possibly need debridement? (Photo)

Dear jm141414,this type of wound is not uncommon after breast reduction. It is usually caused by poor blood flow. I would suggest you to consult your plastic surgeon, follow your surgeon's instructions and keep your wound clean and covered. It can take few weeks or months for wound to fully heal. Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

The photos suggest your incision may have delayed healing, possibly due to blood supply issues. Your surgeon may debride the scabbed over area once it begins to demarcate and separate, or could choose to do it earlier, depending on individual findings and the surgeon's preferred approach. For now it may serve as a biological dressing over the healing deeper tissues in that area, so it is not uncommon to leave it in place as long as it is not infected. However, nobody can give you specific advice without an examination so you should follow up regularly with your surgeon.

After reviewing your photos and with  the time frame of 3 weeks after surgery I would recommend that you have a debridement of the devitalized tissue sooner rather than later.  It is my experience that after a certain amount of time the devitalized tissue can act as a starting point for a wound infection. I am sure your surgeon will lead you in the proper direction.  Good Luck