Each WeWork office has an SPE that's just for that lease. Every landload wants WeWork on the lease, but won't get it, as WeWork tends to have significant leverage with either the space that they're going after or the desire to have WeWork on the rent roll.
When things are booming, WeWork is advantageous for landlords, and appraisers/the market/potential buyers will underwrite that space positively.
However, there's minimal guarantees that WeWork will actually pay long term, or that you'll have any legal recourse. On top of that there are significant capital costs to a WeWork lease that landlords have to shell out up front. Their leases are typically structured with a lot of free rent up front, so the break even point for a landlord may be many months or years farther out than a typical tenant leasing comparable space.
The losers in the WeWork deal are the landlords, as they're bearing a lot of the risk, and get minimal upside. I'd expect to see a high degree of correlation between WeWork's IPO/stock price and REIT valuations. Underwriting will push the value of a WeWork lease if they can, which will only give more momentum to the bubble.
Source: Worked at a nationally invested REIT that had several WeWork leases in our portfolio