I'm predicting that the answer you'll get is that if there are no pax vacancies in the base you want, you keep flying freighter and stay on the freighter payscale until you are awarded a pax vacancy. And if there are more than a few opting to go on cos. 08 and in effect get their pax award on that base you're sh!t out of luck for a while since there won't be any vacancies for a while.
That letter saying "last ftr fo committment done then no fo ftr" is not worth the paper it was written on due to the last line saying it's subject to change. It means nothing. And it only talks about "pax vacancies" anyway. Depending on how many take the cos. 08 on the bases you want there may not be a pax vacancy for a very long time! And don't think this bunch would not love to let you get old on the ftr payscale forever if my prediction is correct. They are extremely vindictive. That's the only reason I might take cos. 08.
Correct me if I'm wrong, anyone!