Interesting question. I don't have a cast-in-cement answer, but this may shed some light. I saw a price drop for one of my 2020 cruises some weeks back. Sent email to my PVP to ask her for the adjustment, but got an autoreply that she was out of the office for a few days. I didn't know how long the price would stay down, so I called Princess to ask for the refaring. The person that took care of it for me went through some checking: any promos - no, non-refundable deposit - no. Then she told me that she could take care of it without any problems. That makes me believe that this particular Princess rep - note the qualification there - thought that if the deposit was non-refundable then I'd lose it. Take that with a huge chunk of salt, rather than a grain. Probably depends on who you speak to.