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.