$20B is optimistic, but not outside the realm of possibility if they can show revenue growth by filling the inventory they've been building, at the same time they drastically curtail the cash burn needed to obtain still more inventory. They're on track for a 50% increase in 2019 revenue over 2018 revenue, and if that growth continues into 2020, then an IPO in a year wouldn't be completely unreasonable at 5x revenue on the basis of continued revenue growth. Still a bit high for a traditional real estate company, but they may still have some tech-adjacent mojo to prop it all up. It's a longshot, but not impossible.

It seems unlikely to stop selling space at a loss while maintaining revenue growth. After all, if they can do that, why didn't they already?