I think this depends on the mall format.
Malls as an endless row of stores, yeah, that's becoming obsolete. I think malls that can offer a healthy mix of stores, restaurants, and entertainment can still succeed. And there will always be some products\services you just can't get online. Satisfy one of the multiple reasons people might be willing to be in the area and they'll end up frequenting the other options you provide.
Agreed.
I think their greatest asset might simply be the sunk costs involved.
Malls have already cleared the hurdles of...
-- going through the commercial and regulatory procedures of being permitted, contracted, and built, none of which are fun processes for any real estate developers
-- while the configuration of the land, decorum, and structure... lots of surface parking, the internal structure, the like... is not exactly what you might build from scratch, having a building to modify is a heck of a lot easier and cheaper than a new build
-- they tend to have good, known, recognized locations and, where applicable, cities have usually made some accommodations in their transportation systems to help them succeed and/or built their public transit systems around them, as well
I guess I might have my image of "the mall" tainted by North Grand growing up, which was exactly the endless row of stores that you described in your message.
As retrofitted mixed-use developments, they could do quite well.
The ones out here are doing exactly that...
https://www.tysonscornercenter.com/
https://dc.curbed.com/2018/2/7/16986356/ballston-quarter-entertainment-hub
...and seem to be doing great for it.
Des Moines is not Arlington or Fairfax County, though.