Location, Location, Location, that's the real estate mantra that still applies in the virtual world. Somewhere someone is going to create a virtual world where many people (millions?) will spend their time. That's where virtual real estate will have value. Specially if you can get income from it. Virtual real estate is crap now but give it time.
Imagine if Facebook sold a specific area in their website. Let's say it's the upper right inch of every user's screen. What's that real estate worth? Now apply that idea to a virtual world. Ya, you can add real estate forever but only certain areas will have value.
It's the same situation in the real world. You can buy an acre of land in New York city that will cost millions. You can also buy an acre in the middle of the Mojave desert that will cost a tiny fraction of that. They are both real estate. Only New York will be worth millions now and for however long New York keeps it's popularity.
No it isn't. In the real world you must travel through space to get from point A to B. The real world requires you to move from location to location in a relatively linear fashion, making certain locations of higher value. Certain locations have better resources, infrastructure, culture, etc etc. All of this is unlimited in VR. If it's limited, that limitation is completely artificial, and anyone can spin up their own new world with better everything.
Without reading the article, my opinion is that whatever potential exists in this idea is rooted in the fact that people buy all sorts of things in video games all the time. Buying virtual things in video games is wildly popular.