Will my implants soften up and squish together to form a cleavage? (Photos)

At 17 days you are about 13 percent settled, softened, shaped, dropped and fluffed. When fully settled, the increased volume of your breasts will make it easier to create cleavage in clothes. "Drop and fluff" refers to the fact that as the skin stretches and the muscles relax, the implants move down and out slowly – about 1 percent a day. It’ll be about six weeks before they even begin to settle down, but they’ll be close to 80 percent settled and softened at three months. Watching their progress is like watching your hair grow. You don’t see a difference in your hair growth daily, but all of a sudden you need a haircut. 
Be patient after surgery. Give yourself a few months before making a judgment about your surgical results. You won't know the outcome until then. 
Dr. Ted Eisenberg, Board Certified Plastic Surgeon and Author

Will my implant soften up?  I appreciate your question very much. It is normal for breast to feel a firmer right after surgery. The average patient to soften up quite nicely and her cleavage improved as well in the drop and fluff stages of healing. Cleavage is often times limited by the natural anatomy the patient brings to the table. Your photos suggest you have strong muscles and they may provide you with a limitation in how much cleavage can be achieved.   I suggest you discuss this concern with your plastic surgeon in great detail to get a better idea of what your final results might look like. Have a lovely day, Dr. Aldo

At only 17 days post op I would say there is a 99.999% likelihood that your implants will soften and your skin will stretch.  You will notice a huge difference over the next couple months and some continued smaller degrees of settling for up to 6 months.