We had our first look at Mozilla's Firefox OS back in February of this year, and the HTML5-heavy operating system will eventually target developing markets where low-cost smartphones are the trend. Unfortunately, even though Sprint backs the new mobile operating system, it may never land in consumer hands in the U.S.

"Currently, there are no plans to launch in the US," Mozilla executive chair Mitchell Baker told CNET recently. The company will provide U.S-based developers with units, such as the ZTE Open, though it doesn't sound like there's going to be a consumer-focused launch here.

Perhaps Mozilla just knows its strengths: markets like Latin America and China, where carrier subsidies aren't the norm, are more likely to adopt an affordable handset. After all, Motorola is playing to similar strengths with its Moto G. While that phone will launch in the U.S. at a super affordable off-carrier price, the real focus is to get people in emerging markets connected to the Internet at a low-cost.

The U.S. market is a tough one to crack right now. Android and iOS have the dominant market share here, and Windows Phones from Nokia, which are arguably more powerful than Firefox devices, are helping Microsoft's platform gain traction in third place. BlackBerry is falling off the map, and perhaps Mozilla knows there might not be enough room for a low-end fourth player here.