Can't they just sell real estate? I mean, remote working is not a thing for the vast majority of jobs out there, so office space is still a valuable asset. So if you are in IT and have offices that are not going to be used (because your employees want to work from home) then just sell/rent it to other companies in which their employees cannot work from home.
For smaller companies this is likely feasible. But for Apple/Google/etc, I imagine there were a lot of architectural / design decisions that went into their campuses that assumed a single monolithic tenant working in a largely open-office format.
That probably makes those spaces harder to sell/rent. It's unlikely they'll find a single large buyer with the same needs. They'd probably have redesign the campuses a bit to better support multiple tenants.
Those companies have massive amount of plain office space too. Like, Apple has half the office space in Cupertino and plenty more in Sunnyvale. They are certainly not fretting about suddenly having too much spaceship on their hands.
This just in, "Dear fulfillment center staff, you now have access to free coffee, a gym, and a great cafeteria but will still need to urinate in bottles to meet expectations. If you clock in early you can grab a free coffee! Just think of it as a beautiful environment for you to slave away in, your industry peers will be envious of all the perks you have access to but can never enjoy." --Amazon Logistics Management
To be fair, Apple and Google have tons, tons, and tons of real estate in the Bay Area, not to mention globally. They would probably sell those other non-iconic "basic office buildings" before thinking about selling their main campuses. I mean if you drive through Mountain View and Cupertino, there are entire streets where every building is a Google or Apple building. Plenty for them to sell and still keep their headquarters.
