Delayed wound healing: big hole. Will I stay having a big hole? (Photos)

First and foremost, do not worry!  This will heal either on its own with wound care or with a small procedure to stitch together.This problem does occur although not that common.  Treatment varies amongst plastic surgeons.  Based on your pictures, I would remove those stitches so that the open wound could be treated more thoroughly.  Other than that, I agree with your physician.Dr Spies

Congratulations on having undergone the tummy tuck procedure. These types of incision line healing problems are not uncommonly encountered after tummy tuck surgery.   Generally, these types of incision line healing problems are self-limited and heal over the course of a few weeks.   Sometimes the area may look worse, before it looks better, usually by the two month post mark.  Sometimes, removal of unhealthy tissue and/or exposed sutures may help expedite the healing process. 
Wound care regimens will differ from one plastic surgeon to another. Generally, this will involve application of some type of sterile dressing ( in my practice I use a non-stick dressing covered by a sterile dressing). You should have peace of mind that these types of wound healing problems generally go on to heal over the course of the next several weeks, often without long-term sequelae. Also important to concentrate on a healthy diet, including good protein source.  Best wishes.