@evleaks just posted an alleged HTC M8 wallpaper on Twitter (see it on the left). There’s nothing too exciting about the wallpaper itself, but the original image - hosted on Google Docs - has 2160 x 1920 pixels. As you may know, this is exactly the pixel resolution of scrollable wallpapers made for 1080p Android smartphones. Ergo, the M8 should be a 1080p device.
Since @evleaks is one of the most reliable sources when it comes to leaked information, we should take this with little to no grains of salt.
We heard that the M8 (possibly called HTC One+, or HTC One 2 when it hits the market) would feature a 5-inch touchscreen panel, Android 4.4 KitKat with Sense 6.0 UI, quad-core Qualcomm Snapdragon processor, and a dual-sensor UltraPixel rear camera. At 5 inches, a 1080 x 1920 pixel resolution would provide a 441 ppi density, which should be just fine, if not excellent, even if new Quad HD smartphones will be available later this year.
An HTC M8X also appeared recently, but it’s not clear how (or if) this is different from the M8. In any case, HTC is probably getting really close to announcing its new high-end smartphone - it might do it next month, or in March - so everything should be clarified very soon.