So as regards to just not flying the last segment of a Oneworld Explorer ticket, I found this in the FAQ sticky:

"If you need to cancel after departure, all tickets other than those originating in SWP (no penalty) or Japan (lower of 10% penalty or JPY50,000) incur a 10% penalty. You may get a refund of the unused portion of your ticket based on the cost of the flights used to date and the penalty due."

But earlier on another thread I was told my have to pay the point to point fare.

Which is correct - or do I have to pay both a penalty and the fare??

One other option - what if I check in for my final flight but don't board??? Would I still have to pay a penalty? I know that is really sneaky but I can't afford to pay the point to point fare.