Thank you for that clear explanation, iflyjetz. It's a shame to hear, but understandable. We have been able to fly premium economy, booking one-way fares, this past year+ precisely because the fares have been so reasonable. Sad to realize it will be their demise.
And you are correct, I receive an email several times a week offering sale prices on seats. I hope they find a way to survive while also retaining a competitive price, even if it has to increase somewhat.