Google's website all but confirmed the next release to be Android M. And the fact that the update is called Android M in official documentation is exciting to us because it probably means that we'll see Google release an early Android M preview ahead of the official public release.
If the Android M listing is any indication (and we think that it is), Google will announce the update as Android M leaving its official title for an announcement later this year, probably alongside new Nexus hardware.
It also means that we could see an early Android M developer preview. Google's developer previews are like iOS betas in that they're unfinished. That said, it's always exciting to use a new operating system ahead of the public release.
Android M also confirms this update as Android 5.0 Lollipop's successor which means that it will be larger than your standard Android update. Much bigger than Android 5.1.1 that's rolling out right now. That in and of itself is exciting.