It seems that the Google Play Edition (GPE) devices might be done for. As of today, Google is no longer selling the HTC One (M8) Google Play Edition. This was the only device available for sale, so for now this program is closed.
While it could be a stock issue, the program also could be closing. With not as many manufacturers putting out GPE devices last year and the Nexus 6 costing $649 unlocked, it seems more likely that the latter is the case.
However, since this device exists in some peoples’ pockets (along with a few older models), updates will most likely still be put out, especially considering HTC’s Advantage program gives users updates for two years. And even if you have the Sense version of this phone, you will still be able to flash a GPE firmware for it.
So for now, the Google Play Edition program has ended. It’s possible that Google could reinstate it with a manufacturer that would like to, but for now, it’s done.