HTC M8 is the successor to the HTC One, the phone image leaked last week. It is expected to be released late March if the tweet from prolific leaker @evleaks is to be believed, the launch date is not announced and schedules might change. According to him it will be released at an event in New York around late March.
HTC might keep the design language of One series of smartphones in M8 as well, but one thing is changing according to leaks. HTC is going for on-screen buttons instead of capacitive buttons. If this is true then M8 becomes the first device from HTC with on-screen buttons. Google is encouraging manufacturers to use the on-screen buttons in place of physical buttons. Android has in-built support for on-screen buttons, Google Nexus phone came with these buttons first.
The above image is leaked to weibo claiming to be the HTC M8 on-screen buttons. The image shows that the back button design has been changed while the other two buttons align with the HTC One capacitive buttons.
Another rumor is that HTC M8 will come in 4 colors right from the launch according to Shen Ye. HTC usually releases in one or two colors and then releases other colors later at some point, this is the first time it is going with 4 colors for its flagship right from the launch.