Exactly - it all depends on a lot of variables as to whether the ship will wait or not. Things like the tides, the port crew, how many are delayed, how much time they have to get to the first port, etc.
If you're lucky enough to get through to Princess' in-transit phone number (not an easy thing nowadays), they will work to re-route you. If you can't get through in a timely manner, you'll have to handle it yourself and apply for reimbursement from insurance.