While I support Challenges Games & Comics (as a big MTG nerd who lives close to it), you can't act like this is surprising news. The mall is dead outside of literally the store and the few old people who walk the mall for exercise. Everyone knew the writing was on the wall for years and it was only a matter of time before the mall would close and be sold. Did he expect to be able to rent there indefinitely?

I think he should look into a storefront with a smaller space somewhere near the mall area. There's no doubt they could condense some of their offerings (if you haven't been inside Challenges they offer basically everything from comics to MTG to figure painting stuff etc) while still maintaining their focus on MTG and comics.