So far, the OS had taken off with the smartphones running it but the number of features for this OS surely is inferior or something compared to the popular OSes which are not secure nowadays. The next plan from Mozilla will be to bring this OS to the TV and tablets. Sort of like browsing the Firefox browser on TV and tablets for real in Firefox OS similar to Chrome OS except in a little bit secure way.
Some companies like Panasonic are already to launch Firefox OS TVs this year which will be intially as expensive as the smart TVs today in the first place. Ultra HD TVs are like the serious nightmares to buy as if they have the price of the car!
Also, having so much low-end devices like that running OSes like this is not gonna be worth the greatness of the performance. Not to mention the lack of the competitor of the App Store, Google Play like store for Firefox OS which can make things pointless for its future and especially when there will be additional announcements that extend the disaster. So, where are the med-end devices and above? Why is this so prototyp-ish like that? Unless, there are sufficient features, there will be no point in getting TVs or tablets running this in the future.