Google's been on a roll when it comes to sending former AOSP apps to the Play Store for everyone to enjoy (and Google to close the source on), we've already seen properties like Google Keyboard and Calendar, but now it looks like the newly-refresh Email app could be on the way.
A seemingly small and somewhat vague code commit in AOSP to said app clues us in, revealing that Google has likely been testing the app on its internal Play Store. This particular commit served only to update the version of the app, presumably as a way to determine if the update procedure would work properly when downloaded from the Play Store.
It's all we have to go off of for now, but the fact that the stock email app got a huge Gmail-like refresh in Android 4.4 would support the conclusion that Google is probably keen on getting it to a wider audience, particularly since there really aren't many well-designed, modern-looking 3rd party email clients available for Android. And given how often the stock email apps included by device OEMs kind-of-sort-of really suck, this is bound to be something that will please a whole lot of people.
We can only hope it comes sooner rather than later.