When the first Nexus 7 launched in 2012, developers began working on a tweaked interface that has come to be known as the Phablet UI. It is similar to the standard tablet layout that is found on the Nexus 10 and it's not a smartphone layout either. This Phablet UI combines the two designs in an attempt to create something new and useful. The Phablet UI switches between a phone and a tablet layout based on the orientation of the device or which application you are using. You can tweak this setup pretty much however you like, and users are beginning to embrace the setup on 7 inch tablets like the Nexus 7. It has its downsides, though. The Phablet UI affects the SystemUI.apk in a way that makes the notification area and the Android soft keys to become separated. This results in a UI that takes up more display space. Some users don't like this extra screen real estate being eaten up, even on 7 inch tablets.
With the release of Paranoid Android, we can switch between both the smartphone and tablet layouts and DPI (dots per inch) on an app-by-app basis. If we want to, we can keep all of the applications at the default settings and just modify the SystemUI.apk to display in the tablet layout. This method allows us to keep the softkey area and notification area combined, saving that precious screen real estate. Now this is all possible on the new (2013) Nexus 7.
XDA Forums member Caldair has combined the work of several developers, putting it all together so you can get the Tablet UI for SystemUI.apk, as long as you are running the stock, rooted JSS15Q build. Applying the modification does not seem to play very well with the stock launcher, so you will need to install a third-party launcher like Nova or Apex Launcher. Also, the Quick Settings toggles don't work once the modification has been applied. This may be a deal breaker for some of you. Even so, this mod is something to take a look at and decide if it's something that you like. The dev has even made restore files available, so if you get into it and decide it's not for you, you can easily flash your new Nexus 7 back to how it was before the mod.
You can find everything you need in the original XDA Forums thread. Head on over and check it out.