I think the new terminal is a whole lot better than the old one and I don't think the failings of retail are entirely of it's making. The plans for the airport showed quite a different layout with much more space for retail, most of it airside. Simply put there is no attractive retail option airside, no wonder revenues are falling. I don't know if any of you have seen the new "Biza" store at T1 in MAN. It is more akin to BT than Penney's, maybe the CAA (and/or DAA) should just let the pro's to it.
The logical plan might be to move the glass divider so the restaurant is airside move the bar and lounge above their current positions and put retail space in their place. Don't think there is the cash or the will to do that though.