Those who were there at the beginning of the Valve Linux Offensive (circa 2012) will remember Gabe Newell stating that the main driver for investing in Linux is their dependency on Windows as a platform. Valve has never been one for dependencies at the best of times (creating their own engine to replace quake, creating their own sales platform to replace retail) and having a dependency on a platform that explicitly seems to be trying to emulate the iOS/Android approach more and more is absolutely a reason to at the very least have a plan B.
Having Valve come out and say that they're still invested in Linux is important, but what is highlighted in the post is also poignant - in 2012 it seemed the barrier to adoption was interest in the platform and access to a Linux machine. The solution to both of these was to create a high-profile, easily accessible form factor which was Linux by default. It turns out that this may not have actually been the right solution. Linux adoption has risen and the back catalogue of available games has increased incredibly, despite lacklustre sales. The problem now, and perhaps always was the graphics APIs and cost of porting. Valve are actively investing in Vulkan which is absolutely the right thing for them to be doing. The only downside is that it looks like they're neglecting the 'movement' they started with Steam Machines.
I hope to see big things from Valve in the future. If I were them, however, I would invest in creating a truly fantastic desktop experience with seamless transition from Windows, lots of toys to play with, riced desktops etc. Hardware and the console form factor should be secondary to creating a PC desktop experience worthy of the people who created Half Life and steam.