'Profound uncertainty'
Shopping habits have changed, leaving supermarket chiefs wondering what do to with their cavernous stores.
"I've never seen such profound uncertainty; everything is up for grabs," says veteran retail industry expert Richard Hyman.
For shoppers it means that supermarkets are likely to look very different in years to come.
The biggest stores could become more like department stores and also house other services like gyms, nail bars and parcel collection points.
But what's prompting this "profound uncertainty" and urgent need for change?