They may not do the manufacturing themselves, but it's clear that they see a future market for some form of Linux based games system for which they will be the main supplier of software.
It's either that or they are predicting a sharp upsurge in Linux usage after Windows 8 which seems like a very scary predication to make.
Gabe Newell has been publically denigrating Windows 8, but I think his real fear, and this idea would support the move to Linux, is the way Windows is moving towards a closed app store model, which brings it into direct competition with Steam.
It's either that or they are predicting a sharp upsurge in Linux usage after Windows 8 which seems like a very scary predication to make.