I'd attribute the decline of those two enclosed malls to two things. First is the Destiny competition. More than that, I think, was the shift in consumer habits from enclosed malls to plazas. Both Great Northern and Shoppingtown started to bleed tenants when developers (might be COR in both instances, certainly was in Fayetteville) built large new plazas (they call them 'town centers' but give me a break, it's a retail strip in a big surface parking lot) with generous tenant improvement incentives not far from those two malls. A couple national retailers jump ship when their leases expire, a couple more follow suit, and the thing snowballs. Once the malls lost momentum (and disinvestment by Macerich, owner of both malls, also contributed to the problem), they got caught in a bad cycle: need for capital improvements, less lease revenue coming in, less incentive for tenants to stay when leases expire. Once a couple anchors got into trouble, that was the last nail in the coffin.
I don't know as much about Great Northern, but Shoppingtown was a potential goldmine five or ten years ago - one of the most attractive zip codes in the region, and almost adjacent to what's going to be a high-visibility interchange on the potential new I-81. Whole Foods was scratching around the immediate area for its first local store; with a committed developer, I believe they could've landed there. All of this was just waiting for the pendulum to swing back, just as it did from DeWitt to Fayetteville a decade or so before. But the current absentee owner is struggling and now they've lost Macy's, JCPenney, and the library.