Circle Pacific ?
 

I have a circle pacific flight booked that I might not be able to take. I'd like to use it sometime in the future.

If I understand correctly, canceling will cost me 10%. Can I just put it on hold or otherwise suspend it? Do I have to rebook to another date as a placeholder, then rebook again when I know when I can go? Would each of these cost me $150?

Is there a limit how far in the future I can push this?

It's booked at the old price, by the way.

Look here for the rules (particularly section 16):

• oneworld Circle Pacific rule sheet

Since it's booked at "the old price" it must be already ticketed in which case if you can't travel on the First international an/or preceding sectors as booked then your only option is cancellation.

All of this is covered in the Rules.

Cancellation or no show of the first international flight is indeed 10% (or 11% if ex-Australia)

You can't change the flights up to and including the first international flight. Other date changes are free. You don't need to have placeholders. Segments can be open, or you can simply "no show" (although I would be a bit uncomfortable doing that if it's an e-ticket).

The ticket validity is 12 months from the date of the first flight.