Normal Looking Breasts After Explant Surgery?

Breast volume and shape after implant removal can vary based on a number of variables, including your pre surgery breast volume, implant volume, age, duration of implant, skin laxity etc. Since you had saline implants you can actually deflate them preoperatively to get a sense of how much breast tissue you have left. This also allows the breast tissue to rebound from having the pressure of the implant removed and the skin can contract to some degree. Then you can make a final decision about needing a lift, new implant or fat transfer. See a board certified plastic surgeon to discuss all of your options. 

Following explant, there is bound to be some degree of deflation and skin laxity. Some of the skin will recoil, but, depending upon the volume lost (in your case significant), some of the skin will not snap back and remain lax. Often times, these patients will need a lift/mastopexy, if they chose not to replace the volume lost.
With regards to your specific question, I would expect some skin laxity post explantation, at least initially. You have youth on your side which may allow for greater recoil due to the inherent elasticity of the skin. Ultimately, this often a function of the degree to which the skin was initially stretched with augmentation. This may take several months to settle.
However, if the snap back is not satisfactory, this may necessitate a lift. Explant and lift do not necessarily have to be done simultaneously. You could stage the procedure if you are hoping to avoid the scar burden associated with lift. This would allow you to evaluate the appearance of your post explantation breasts and then decide whether to proceed with a lift.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).

There are many factors that go into determining how your breasts may look after removing the implants.  Some include the amount of breast tissue you have, the size of the implants, your skin elasticity, and the length of time the implants have been in place.  Many women elect to have a breast lift performed when the implants are removed in order to address shape concerns.  The best place to begin is a consultation with a board certified plastic surgeon near you.