HTC is preparing a successor to the One for release in 2014, codenamed 'M8', and today the device has been allegedly pictured in a leaked image. The most interesting thing about this leak is the rear of the device: it's styled in a very similar way to the HTC One, yet there are two visible camera lenses, one above the seam and one in its traditional position.
One of these camera lenses is smaller than the other, leading some to speculate that the additional lens could in fact be a fingerprint sensor, with the device retaining a single 'Ultrapixel' camera. However a report from Bloomberg back in January suggested the M8 would pack twin camera sensors, and this seems more likely than an awkwardly-placed fingerprint sensor.
The two camera modules could potentially be used to allow Lytro-style image refocusing after the shot is taken. Toshiba has been working on such a dual-sensor camera design, and HTC may have adapted this for its upcoming flagship. HTC focused much of its smartphone development on the One's camera and accompanying software, so it fits that HTC is adding even more camera capabilities in the M8.
Another image of the M8 shows a device without any capacitive hardware buttons, fueling speculation that the device will use on-screen buttons instead. It's not clear when the device will be launched - it could be at MWC at the end of the month, or sometime in March - but the M8 gets more interesting with each piece of information.