The multiple crises impacting the U.S. economy — the botched response to the coronavirus and the resulting economic fallout, and lack of spending power — have delivered a new gut punch to brick-and-mortar retail, a sector that was already reeling. More than half of all U.S. department stores in malls will be gone by 2021, one real estate research firm predicts, and surviving retailers may not be far behind; once-mighty brands such as Cheesecake Factory and the Gap are skipping rent payments, Starbucks is closing physical locations, and developers see a future for big box stores as office complexes.