Trends started going from WinForms to web around 2000 as pushback against Microsoft so here we are today. I still think from a business standpoint, it was a very expensive thing to do.
Removing WinForms will disenfranchise a large group of developers, that for one reason or another, it could just be stubbornness, won't switch. Microsoft will sooner kill of WPF than WinForms, to not lose those developers. At least that's my belief.
But we're talking for desktop applications only.
As for the official statement, here is the InfoQ overview of BUILD 2014.
https://www.infoq.com/news/2014/04/WPF-QA
"Windows Forms is continuing to be supported, but in maintenance mode. They will fix bugs as they are discovered, but new functionality is off the table. Oh, they stress that it isn’t called “WinForms”."
As I don't have time to search for the video on Channel 9.
The Roadmap for WPF
https://blogs.msdn.microsoft.com/dotnet/2014/11/12/the-roadm...
The developers that have still not abandoned WinForms will not jump shit when the next thing hits either. To keep the huge group of WinForms developers happy, Microsoft will continue to support and develop Winforms. For many, WinForms are still the fasted way to develop simple applications.
So if you want develop for the Windows (desktop) platform, WinForms will be a clear winner for many many years into the future.