Hard to know what net impact will be. They aren’t getting rid of space, just allowing digital first. Fewer people in the office, but Covid19 may result in people in the office getting more space per person than previously.
The productivity gains of WFH might be only in comparison to awful open office plans, and may disappear when compared to more private office layouts. There are still major questions about long term impact to new hires and their growth, where retention takes a hit (employees feel more like free agents and consequently switch jobs more frequently), etc.
It seems incredibly short sighted to be making these decisions on the basis of a 3 month experiment with confounding factors (to say the least!).