[NickNameNick]

Android, the operating system, doesn't care at all if you replace the dialler, or the home screen app, or any other app.

What did happen about a year ago is google moved some of the communication framework stuff from android proper, and rolled it into 'google play services' so that it can be updated independently of the version of android on your phone.

As a result, apps like hangouts, plus, maps, the dialer and others which rely on those frameworks can be updated to use the newest version of the framework without worrying about the whether your population of phones have been updated to android x.y, any phone that has the play store installed and updated should be running a recent version of play services.