Can I downsize to C cup moderate plus without lift 10 years after D cup high profile silicone implant?

Dear BAquestions23,
it is hard to tell for sure without an examination. If you are considering surgery, I would suggest you consult a board-certified plastic surgeon. Only after a thorough examination, you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

I would suggest choosing a size that will fit your frame and tissue and be suitable at any age. Otherwise, with too large of an implant, your tissue is stretched and thinned and loses support. Plus, if it is too thin, a lift may not be possible. Implants do not have to be replaced every ten years. It is recommended to get an ultrasound or mammogram every 3 years for the first 10 years, then every other year for the next 10 years, and then yearly after 20 years. If ruptured, then exchange.