I wonder how much revenue those "duty free" shops really make? I never ever buy anything there as it's a pain to carry stuff with you all the rest of your trip and prices and product selection are totally unattractive to me. It's fun at remote vacation spots to see how well very basic plain vanilla functional airports without all the shopping and mall fanfare do work with only short distances to walk and easy processes.
Many real world malls are dying these days maybe airport malls will too?
What everybody seems to need is a cafe maybe a restaurant and something like a bookshop and early announced departure gates not last minute only.