They will be in Regus/IWG the next week, and a week after that will have forgotten that WeWork ever existed.
So not likely IWG could absorb significant percentages of WeWork customers on short notice.
Far larger players like SoftBank, Blackstone or KKR would be all over scooping up the bones of WeWork. There's certainly no scenario where WeWork doesn't end up in the belly of a private equity company, or a large real-estate holding company. The next recession will destroy them. They'll be lucky if they survive even outside of a recessionary environment.
This analysis looks very different if you do it not in dollars but in sq ft, or in desks. IWG is much bigger than WeWork, but realistically valued.