From look of things it seems Google is planning to stop selling Google Play Edition devices, because few days earlier Google stopped selling of Galaxy S4 GPE. After that HTC M8 GPE was the only GPE Smartphone device available on Google Play store. Now this device is also no longer available. This might be the end of entire series of Google Play Edition devices.
As you already know that main difference between normal and GPE device is that GPE devices receives direct Stock Android version from Google. HTC M8 GPE recently updated with latest Android Lollipop version without Sense UI.
Google didn't officially close its Google Play Edition line-up, that’s why there are
chances Google might introduce new devices in few months but there are very rare chances of that. Last year Samsung introduced Galaxy S5 but Google didn't
release Google Play Edition of that device and since then no other device added by Google.
On the other hand, if you wanted to buy 5 inches device with stock Android version, then you should grab Nexus 5 because it won’t be available by the start of second quarter of this year.
source: Google Play