In the series of updating all the Google Apps to material design, the default Google keyboard has been updated to ver 4.0 with Material UI theme, which previously had the Holo theme.
And more to that, you can keep the previous Holo theme (White & Blue) or change it to Material Design (Light & Dark) theme.
It hasn’t been updated to Playstore yet, but yes, we have got the .apk for you to install manually.
So, go ahead, and try the all new Google Keyboard with Material theme, until you get Lollipop for your device, if eligible.
Download Link