It looks like Google has finally implementing a workaround/fix for surpassing the 65K method limit of dex files.
About the 65K Reference Limit
Android application (APK) files contain executable bytecode files in the form of Dalvik Executable (DEX) files, which contain the compiled code used to run your app. The Dalvik Executable specification limits the total number of methods that can be referenced within a single DEX file to 65,536, including Android framework methods, library methods, and methods in your own code. Getting past this limit requires that you configure your app build process to generate more than one DEX file, known as a multidex configuration.
Multidex support prior to Android 5.0
Versions of the platform prior to Android 5.0 use the Dalvik runtime for executing app code. By default, Dalvik limits apps to a single classes.dex bytecode file per APK. In order to get around this limitation, you can use the multidex support library, which becomes part of the primary DEX file of your app and then manages access to the additional DEX files and the code they contain.
Multidex support for Android 5.0 and higher
Android 5.0 and higher uses a runtime called ART which natively supports loading multiple dex files from application APK files. ART performs pre-compilation at application install time which scans for classes(..N).dex files and compiles them into a single .oat file for execution by the Android device. For more information on the Android 5.0 runtime, see Introducing ART.
See: Building Apps with Over 65K Methods
Multidex Support Library
This library provides support for building apps with multiple Dalvik Executable (DEX) files. Apps that reference more than 65536 methods are required to use multidex configurations. For more information about using multidex, see Building Apps with Over 65K Methods.
This library is located in the /extras/android/support/multidex/ directory after you download the Android Support Libraries. The library does not contain user interface resources. To include it in your application project, follow the instructions for Adding libraries without resources.
The Gradle build script dependency identifier for this library is as follows:
com.android.support:multidex:1.0.+ This dependency notation specifies the release version 1.0.0 or higher.
You should still avoid hitting the 65K method limit by actively using proguard and reviewing your dependencies.