You have misunderstood the article. It is not advocating for the return to single address space systems. It is advocating for potential alternatives to the linear address space model.
Here [1] is an operating system that I think fits under the description of what you were talking about
The more I research Singularity, the more I like it. I deep dived into all the design docs years ago and the amount of rethinking existing OS infrastructure is astounding.
Joe Duffy has some great blog posts on Midori (OS based on Singularity) here: http://joeduffyblog.com/2015/11/03/blogging-about-midori/