I think the intended market for FirefoxOS was pretty different than ChromeOS. Wasn't FirefoxOS for low-powered phones? ChromeOS is designed around a "streamlined" laptop system.
Yeah, FFOS essentially had the SteamOS problem - targeting a market that didn't have any 'wedge' users in their existing demographics. For Firefox OS and Steam OS to take off you needed to buy new hardware and the people most on board with this already had hardware and didn't have a use case for buying more (low end phone for Firefox, PC-as-a-console for SteamOS). In either case there was a small pool of first movers and then almost no early adopters. This was pretty stark in the steam case as Linux usage, sales and games rose considerably but hardware sales were pretty thin.
If they refactored Firefox OS to be a ChromeBook competitor, sure. They heavily marketed their phones to the developing world markets.
I may be wrong, but I have a suspicion that Chromebooks only got a foot in the door in the education sector because they had such a large marketing machine behind it. I wouldn't mind betting money that Firefox wouldn't be able to get an equivalent foothold (even comparable to their browser market share right now with like-for-like hardware and form factors) just because their exposure for any given initiative is a fraction of what Google can summon.
