Hopefully Fuchsia doesn't succumb to the same second-system effect.
It doesn't sound it was ever planned to be shipped? It was for experimentation, research and development. And some of that work made its way into Windows. Seems like a success to me.
edit:
> Midori was the code name for a managed code operating system being developed by Microsoft with joint effort of Microsoft Research. It had been reported[2][3] to be a possible commercial implementation of the Singularity operating system, a research project started in 2003 to build a highly dependable operating system in which the kernel, device drivers, and applications are all written in managed code. It was designed for concurrency, and could run a program spread across multiple nodes at once.[4] It also featured a security model that sandboxes applications for increased security.[5] Microsoft had mapped out several possible migration paths from Windows to Midori.[6] The operating system was discontinued some time in 2015, though many of its concepts were rolled into other Microsoft projects.
"Midori was a research/incubation project to explore ways of innovating throughout Microsoft’s software stack. This spanned all aspects, including the programming language, compilers, OS, its services, applications, and the overall programming models. We had a heavy bias towards cloud, concurrency, and safety. The project included novel “cultural” approaches too, being 100% developers and very code-focused, looking more like the Microsoft of today and hopefully tomorrow, than it did the Microsoft of 8 years ago when the project began." [1]
Later some of this ideas became core features on Windows.
For a great overview about Mindori project: [1] http://joeduffyblog.com/2015/11/03/blogging-about-midori/