This article gets more than a smidge of its history wrong. For instance, it makes it seem as if WPF (nee Avalon) was written by DevDiv in isolation from Windows, where in reality the Avalon team was mostly made of the former IE team after its legal dismemberment. In fact, we moved my team (which was focused on developer tools on, for, and made with WPF) from DevDiv buildings into Windows buildings just so we could build apps and tools for Avalon to help test their platform.
But, it was a big effort. And even coming from inside of Windows, getting the rest of the shell to run on a whole new stack -- from drivers, through C++ layers, through managed -- was a challenge, especially with all of the other things going on in Longhorn. Sometimes, you bite off more than you can chew, especially when you make the dependency stack too deep.
Also, all of this happened long before Silverlight efforts started... XAML came out of the WPF work. Arguing Silverlight stole DevDiv focus from WPF during the Longhorn timeframe is temporally impossible. Certainly, you could argue DevDiv was being pulled in many directions with the concurrent efforts to placate the VB4 crowd, push out a new version of VS, figure out a new syntax for Managed C++, compete with the then-rapidly-expanding Java tools ecosystem, and support all of the internal and demanding partners (especially SQL and other Windows efforts). But a substantial portion of both the tools and .NET runtime team's efforts were spent making Avalon perform, and I don't think that even now anybody who was there would claim that more DevDiv resources could have made the "Windows Shell is now made from WPF" effort succeed in the desired schedule.
But, it was a big effort. And even coming from inside of Windows, getting the rest of the shell to run on a whole new stack -- from drivers, through C++ layers, through managed -- was a challenge, especially with all of the other things going on in Longhorn. Sometimes, you bite off more than you can chew, especially when you make the dependency stack too deep.
Also, all of this happened long before Silverlight efforts started... XAML came out of the WPF work. Arguing Silverlight stole DevDiv focus from WPF during the Longhorn timeframe is temporally impossible. Certainly, you could argue DevDiv was being pulled in many directions with the concurrent efforts to placate the VB4 crowd, push out a new version of VS, figure out a new syntax for Managed C++, compete with the then-rapidly-expanding Java tools ecosystem, and support all of the internal and demanding partners (especially SQL and other Windows efforts). But a substantial portion of both the tools and .NET runtime team's efforts were spent making Avalon perform, and I don't think that even now anybody who was there would claim that more DevDiv resources could have made the "Windows Shell is now made from WPF" effort succeed in the desired schedule.