It's late, it's hot and clammy, and work is beckoning early tomorrow morning, so I will keep it short: Omron is showing a Firefox OS phone with a Japanese IME based on their Wnn system for Android at the Wireless Japan exhibition in Tokyo. KDDI is considering introducing a Firefox OS phone in Japan, citing the openness and simplicity of application development as selling points in favour.
Me, I would certainly consider a Firefox OS phone, at least as a companion phone to my Nexus 7 tablet. It'd give me the best of both worlds, with an inexpensive phone that can be mostly a phone with lightweight web apps; and a tablet for running larger, heavier Android apps and games. Most important apps I use are already web apps after all.
Edit: the rest of the interview is paywalled, but let me expand on the point he made about the nascent third-platform ecosystem: Tizen and Microsoft phone are both really just more of the same, and don't actually bring anything new to the market compared to giants Android and IOS. Jolla and Ubuntu Phone do bring interesting new things, but neither are anywhere close to wide rollout yet.
Firefox OS is getting ready for prime-time and really has the same selling proposition as Chrome OS: the web is your application platform. It's meant as a satellite device, so it can be more lightweight — and thus cheaper — than other platforms, and it does an end-run around the application availability problem by simply treating the ever-present online version of stuff as applications in their own right.