HTC has already started rolling out Android 5.0 Lollipop to its main flagship devices from last year and the year prior, being the HTC One M8 and the HTC One M7, along with the many other OEM's who are currently in the process of updating devices to the latest version of the Android OS. While some manufacturers are just now beginning to get Lollipop onto their 2014 flagships, like Sony with the Xperia Z3 and Xperia Z2, HTC is currently testing development of the next version of Lollipop for its GPe version of the HTC One M8.
HTC is targeting an early April release for the Android 5.1 Lollipop software update to hit the Google Play edition of the One M8, which is just a few short weeks away. Customers might be forgiven for being skeptical of the release this quickly given HTC missed their initial 90 day window on updating their regular non-GPe devices to Lollipop, but GPe devices are more or less as close to stock Android on a Nexus device as it gets so the possible time frame isn't out of reach. Coming from Mo Versi in a tweet earlier this morning in response to a user question, the date of early April is based on internal testing of the software as well as Google QA approval.
It is possible that the update could hit later than they're shooting for, but users should be hopeful nonetheless. When Android Lollipop was first initially announced and released, HTC's GPe One M8 and One M7 phones started receiving the updates around the beginning of December, so the wait wasn't long after the software was made official. Android 5.1 Lollipop was just officially announced by Google a few weeks ago, so if the update to 5.1 for HTC's GPE One M8 does hit on schedule, that puts users at a waiting period of about a month and a half, which is close to the same time frame as it was for Android 5.0.1. If you use an HTC One M8 GPe model, keep an eye out for the updated software package to hit your device within the next few weeks, which is also close to the time that HTC is rumored to be launching their brand new HTC One M9.