The 9to5 article is poorly written. In the first paragraph 9to5 says a new window system is "scheduled to replace" the current one, but this is not true. In fact, in the blog post the article cites the Gnome developer Tobias Bernard explicitly says "There’s no timeline or roadmap at this stage". The Gnome developers are merely experimenting with a new window management system and at this early stage it's impossible to know what the finished product may look like if these experiments go anywhere at all.

Here's a link to the original blog post where Tobias explains their dissatisfaction with existing window management systems and discusses the techinical challeneges developers face.