Internet Explorer 11 will remain unchanged, which is included on non-mobile versions of Windows 10, to provided the required legacy support in an Enterprise environment. Devices that run non-mobile versions of Windows 10 will have both Internet Explorer 11 and Microsoft Edge on them.
It should be noted that the linked article in the author's question describes Microsoft's original plan for Microsoft Edge and Internet Explorer 11. I am pointing to the Microsoft blog on purpose since thats what the base information in the linked article is from.
The current plan is described in following article article with the following image. This is an adaption of another answer I made, which answers this answer, removed any content that didn't apply to this question.
Project Spartan was built for the next generation of the Web, taking
the unique opportunity provided by Windows 10 to build a browser with
a modern architecture and service model for Windows as a Service. This
clean separation of legacy and new will enable us to deliver on that
promise. Our testing with Project Spartan has shown that it is on
track to be highly compatible with the modern Web, which means the
legacy engine isn’t needed for compatibility.
For Internet Explorer 11 on Windows 10 to be an effective solution for
legacy scenarios and enterprise customers, it needs to behave
consistently with Internet Explorer 11 on Windows 7 and Windows 8.1.
Hosting our new engine in Internet Explorer 11 has compatibility
implications that impact this promise and would have made the browser
behave differently on Windows 10.