I guess you just change the locks and see how much you can get for a cold brew kegarator on Craigslist.
I think there will be a lot of simply assuming the contracts. WeWork was predicated on this idea that you had a "membership" that allowed you to jet around to all these other offices all over the place and I think that business model is done for a few years at least. At which point you recognize that your landlord isn't WeWork, it's whoever actually owns the building. I've probably linked these guys a half-dozen times; subleasing isn't fucking rocket science.
THIS. WeWork goes away, but the tenants stay and begin paying slightly higher rents to the building owners. Because the owners don't want the space vacant, anyone paying WeWork's rent can afford a little more, and the building landlord just hires someone to manage all the "small" contracts that were too small for them to consider as renters before. That is, once people are allowed to go inside the buildings again....