Web view compatibility in android 4.x and android 5.0

In my android application I am planning to use the WebView of Android 4.x (API level 19) and I heard that in Android 5.0 (API level 21), there is a plan to release a new web view. So my question is

1. What happen if my application run on the device which is having android 5.0 version?

2. What are the things I need to take care while creating my app?

3. Does sencha touch webview consider/support this above scenarios?

Thanks in advance

~Santosh.

Web view compatibility in android 4.x and android 5.0