I am currently using Eclipse for Android development and have been for a few years.
The page for Android Studio says "Android Studio is the official IDE for Android application development..."
Another page says, "you should migrate to Android Studio to receive all the latest IDE updates".
What do these statements mean for the ADT plugin for Eclipse and how urgent is it that I migrate to Android Studio?
It means that going forward, Google will be working primarily on Android Studio, not the ADT plugin. Google will also not be providing much (if any) support for developing apps in Eclipse moving forward.
You can keep using Eclipse for the foreseeable future without any real problems. However, I wouldn't expect new developer tools to become available to you. For example, a lot of the new features in the Android Studio layout designer will not come to Eclipse.
While upgrading isn't urgent, I highly encourage you to try out Android Studio and try migrating so that you can at least see what is available in Studio and find a migration plan that works for you.
For years, Google employees and daredevil programmers were using an "unofficial", beta version of Android Studio that was deemed not ready for the general public. In November 2014, Google launched Lollipop 5.0 on the Nexus 6, and alongside it, a version of Android Studio that is considered stable enough for the average developer, which they refer to as "official".
While the Eclipse SDK manager continues to provide the latest API platform packages, the ADT toolset for Eclipse is no longer being maintained. I believe the last stable release was in July 2014. Only Android Studio will receive the ADT tools updates. It means you can still continue using Eclipse for a year at least. But over time, the ADT tools for Eclipse will get outdated, and only Android Studio will receive new updates.
Over the next few months, the official documentation and examples will also be updated to support Android Studio. Many companies in the US and Europe have been using Android Studio for a long time now, so you can expect your clients to demand all existing as well as new development to be done using the new IDE.
Further considerations:
NDK integration with Android Studio is still pretty painful. Eclipse may be the only viable option for most NDK devs till the NDK integration process with Studio is improved.
References:
1. Which Android IDE is better - Android Studio or Eclipse?.
