Cannot develop Firebase on Xamarin.Forms 3

The version of Xamarin.Android.Support.Design (27.0.2) is not compatible with Xamarin.Forms 3.0.0.482510.
Constraint: Xamarin.Android.Support.Design (= 23.3.0)
We have a year to replace GCM with Firebase, and we cannot expect all of our users to be on Android 7.