There have been rumors in the past of Valve indulging in the hardware market along the lines of a fully fledged console. Those rumors pretty much died off some time ago, but now Valve’s job listings are sort of reviving the idea. Specifically in the description for the Hardware Engineer opening:
It mentions “hands on prototyping experience” and working with a hardware team to “conceive, design, evaluate, and produce new types of input, output, and platform hardware”. So with this makes it apparent that Valve is at least interested in the idea of creating their own console. Honestly I have no idea how well that would go, they are a large corporation but I wouldn’t know how well they would fare against behemoths like Microsoft and Sony.
In contrast, at least Valve isn’t losing money consistently like Sony is, and at least they whole-heartedly care about video games (specifically PC games) unlike Microsoft. As for Nintendo, well… They’re just doing their own thing. I have no idea how they’re going to fare at all in the future so I can’t even figure them into the equation anymore, it will take some time for the next generation of consoles to come around and be around for a while before we can all draw a clear picture of what the deal is like with this current generation. But if Steam actually indulges in this market, that could be very interesting, very interesting indeed.