<picking up this interesting thread, after about a month>
I work for a Fortune 30 company in Silicon Valley. Observation: the fact that so many people are saving 2-4 hours of daily commute is simultaneously boosting productivity and improving morale, offsetting some of the COVID-19 impact (e.g. having to take time to care for kids, etc.).
We are seeing tech companies competing on how they're extending benefits to employees, and I can see that competition remaining for several years to come at least.
In the long term, companies might be incentivized to keep some flex time approaches in place, especially if they can oversubscribe expensive office space, reducing overheads. Demographically, this could lead toward a gradual spreading of the workforce outside of the traditional tech hubs of the world. I was only half-joking to my wife that we should sell our house, pocket the profit, and move to Hawaii. A couple quarterly "work from the office" stints would be a small price to pay.