The internet, consumer tastes, and most importantly, the demise of mid-tier anchor stores has led to this. When Federated and the May Co. started gobbling up regional chains 15-20 years ago, I don't think anybody foresaw the day when half of the anchor stores would be gone. Two or three department stores have now been replaced by one Macy's. The downfall of Sears has not helped malls either. If a Sears store is still open today, it hasn't seen any significant refreshes or upgrades in the past 15 years since ESL Investments took over. JCP hasn't helped the cause either.

Generally, if shopping centers are surviving, it's because they have been re-developed or re-purposed into mixed use developments with shopping, dining, housing, and office spaces. If they haven't re-developed, then they are likely surviving due to the scarcity of other viable shopping options in a geographical area.