Good new ! for Moto E 1st gen user They can soon Download Android M Rom for Moto E 1st gen 2014
but you have to wait for some time because the Rom was Ported by an Xda developer
on his thread on XDA
and his team and they have already started the development of Android M for Moto E and Hope So it will successful so that we can get Stock Android M 5.2 for Moto E 1st gen 2014 Soon.
This port will be 100% stock Android and will not be changed/ customized.
When Android M is released to the android open source project then They will also make a vanilla ROM running on this version.
Keep visiting this post for further Updates..