Just a little bit of background information beforehand – User Agent Profile (UA Prof) files happen to be specification files which will describe the model, screen size as well as the other features of the device before it ends up on official channels. It is not compulsory for companies to work on such files, but most of the time, whenever an UA Prof file is published, it would be done by the handset manufacturer itself, and also doubles up a kind of confirmation for that particular device.
Having said that, the HTC M8’s resolution is not tipped to change compared to the HTC One, but at least the viewing area will receive a bump – slightly, of course. We are looking at a very possible 5” display, although it might eventually be stretched to hit 5.9”.