For some Android users who are running Lollipop on their devices, the inclusion of heads up notifications in the system for when new messages, emails, or notifications for various apps installed come through is not necessarily considered a blessing. While many users appreciate the new notification system, plenty of users likewise, enjoyed the older version of the way notifications were displayed when they came through to the device during use. This was known as Ticker Text, as the part of the notification displayed in the status bar much like a stock ticker would display its data as notifications came through when you were using the phone. Although it is obvious that Heads up notifications have taken over the role for ticker text now with Lollipop, it's safe to say some users would prefer to stick with the older ticker text option.
Alas, this doesn't appear to be possible, even if you turn heads up notifications off for specific apps in the settings, as Google has confirmed that disabling heads up notifications for any apps will not allow ticker text to show back up. As far as stock Android is concerned, ticker text is gone for the time being (possibly for good) as Google mentions they have no plans to bring it back. That doesn't however mean that it won't be coming back in any other forms, as there is still every possibility that some developer may choose to launch an app which allows the ticker text function to be present on devices.
On the Google code site in a thread about the developer preview of Android M, Google states that while they appreciate people's requests to bring back ticker text, it won't be included in the release version of M. However, they do state that it is still possible for it be included in future releases, which means they haven't entirely abandoned it also. For now, users may as well consider ticker text a dormant feature. One that may very well wake up one day and present itself to the world, but one that may also stay silent for the foreseeable future.