No room on your display? Want to get away soft keys? Well, there's an app for that (You don't say). GMD Auto Hide Soft Keys does it all automaticlly and offers a bunch of options extra!
Simply put, all you need to do/have is root access and have this app installed.
This app can very impressively make room for your display, clean your homescreen and make it simple by hiding soft keys bar away from your launcher.
Soft keys-bar can be opened again by simple swyping up on your display. Isn't that cool?
App should work without any problems on all Nexus devices and Xperia Z. You may try it on your non-listed device also but problems may appear (it worths a shot, though).