Looks like the "fly or die" change eliminates the possibility of re-booking to a lower fare and getting a voucher after being ticketed. This suggests that purchasing tickets at anytime other than during a sale is not a wise move.

Also, I note on the US Air website in the FAQs to the press release, that the non-refundable fares cannot be refunded under any circumstances including military service, jury duty, and even death. How customer friendly is that?